From barber chair to widowmaker: the glossary

Tree work has its own words. Some come from rules, some from the crew. This list gives the plain meaning of each one and says which source backs it.

Usage differs by country, and one word can mean two things. Where a source uses another word for the same thing, the entry says so. Most definitions come from the WorkSafe New Zealand code for arboriculture, the US logging standard 1910.266, the New South Wales tree work code of practice and the Alberta OHS Code definitions. Rigging words have their own page, rigging words by kind.

Same thing, different word

The same job has different names by country. Each row is what the named source calls it.

The thing	The word	Where and source
Notch that steers a fall	undercut	US, OSHA 1910.266
Notch that steers a fall	directional or sink cut	UK, HSE
Notch that steers a fall	scarf	Australia, NSW code
Tree caught on another	lodged tree, hung tree	US, OSHA 1910.266
Tree caught on another	hung up	UK, HSE; Australia, NSW code
Tree caught on another	hung-up tree	New Zealand forestry glossary
Cut or broken limb hanging in a tree	widowmaker	US, OSHA logging eTool
Cut or broken limb hanging in a tree	hanger	New Zealand arboriculture code
Broken piece resting in a canopy	sailer	New Zealand forestry glossary
Sawing a felled tree into lengths	buck, bucking	US, OSHA 1910.266
Sawing a felled tree into lengths	cross cutting	Australia, NSW code
Machine that lifts a worker	aerial device, aerial lift	US, OSHA 1910.67
Machine that lifts a worker	MEWP	UK, HSE; New Zealand code
Machine that lifts a worker	EWP	Australia, NSW code
Machine that chips branches	woodchipper	Australia, NSW code
Machine that chips branches	brush chipper	New Zealand code

A to C

Aerial device: a vehicle-mounted device, telescoping or articulating, used to lift a person to the work. US rules also call it an aerial lift (OSHA 1910.67). The UK HSE and the New Zealand code say MEWP and the New South Wales code says EWP.
Aerial rescue: getting a hurt or stuck climber down from the tree. The New Zealand code says tree work that takes an arborist above three metres needs a second person on site who is trained in it.
Anchor point: the place in the tree the climber's system is attached to. The UK HSE page on tree climbing says each one should be strong enough for the climber, the work equipment and any foreseeable loading. The New South Wales code splits them into natural forks and artificial devices installed in the tree.
Arborist, qualified: in the New Zealand code, a person with a recognised degree, diploma or certificate in arboricultural operations who is familiar with the equipment and hazards and has shown they can do the tasks.
Back cut: a felling cut. OSHA says it must leave enough hinge wood to hold the tree to the stump for most of its fall. The New South Wales code calls it the final release cut, made on the opposite side of the trunk from the scarf.
Barber chair: when the trunk splits as a tree falls. The University of Georgia says it happens when the force pulling forward is enough to split the trunk but not enough to fold the hinge (UGA Extension circular C 1243).
Blocking: in the New South Wales code, taking a trunk down by gradually removing manageable sections after the canopy has gone.
Bore cut: a cut made through the tree. UGA describes an open-faced notch followed by a bore cut through the tree to create the hinge, and lists setback as a risk during a bore cut.
Buck, bucking: cutting a felled tree into logs (OSHA 1910.266). The New South Wales code says cross cutting for the same job.
Bucket truck: a truck carrying an aerial device whose platform is a basket or a bucket. US rules use the term aerial device or aerial lift.
Cambium saver, friction saver: the New Zealand code lists friction saver as another name for cambium saver. The New South Wales code says a friction saver or anchor sling is used at an anchor to reduce friction.
Carabiner (karabiner): a connecting component with a self-locking gate (Alberta OHS Code). The Alberta OHS Code spells it carabiner and the UK HSE spells it karabiner. The New Zealand code lists karabiner and points to carabiner. It says an auto-locking one closes into the locked position by itself and takes at least three distinct movements to open.
Chaps: leg protection worn when running a chainsaw (New South Wales code). The guide on chainsaw protection by country covers what each country's rules say.
Chipper: the machine that chips cut branches and brush. The US logging standard 1910.266 has rules for chippers, including that access covers stay shut until the drum or disc has stopped. The New Zealand code lists brush chippers and stump grinders as training topics.
Climbing line: the rope a climber is attached to in the tree. In the New Zealand code, D-rings on the harness carry the climbing line, and climbing lines are to have a breaking strain of 22 kN when new.
Crew lead: the person in charge of the crew on site. The New Zealand code calls this a foreman or foreperson, "a person nominated by the company as being in control of place of work".
Crotch: the fork where limbs meet. A natural crotch is part of the tree. The New Zealand code calls any other support for the line a false crotch, built with rings or a pulley, and says each part is rated to at least 22 kN.

D to F

Danger tree: a standing tree that is a hazard to workers, for example from damage to the roots, trunk or limbs, or from its lean (OSHA 1910.266).
D-ring: an attachment point on a climbing harness for the climbing line or a work-positioning lanyard (New Zealand code).
Domino felling: partly cutting several trees that are left standing, then pushing them over with a pusher tree (OSHA 1910.266).
Drop start: starting a chainsaw by pushing it away from the body with one hand while pulling the cord with the other. The New Zealand code says this is not an approved work practice. The same code lists the extended arm technique as a way of starting a saw while aloft.
Drop zone: the area where cut pieces land. The New South Wales code defines it as any area in which parts of the tree may be felled or dropped.
Driving trees (tree driving): felling one tree into one or more others to bring them down. The New Zealand forestry glossary defines it that way. OSHA's word for a similar method is domino felling.
Face cut: a felling cut that works with the back cut. OSHA says the back cut sits above a horizontal face cut, except in open face felling, where two angled face cuts are used.
Fell (US: fall): to cut down a tree. The person who does it is a feller, or faller in OSHA's wording.
Felling aids: the UK HSE page for chainsaw operators names breaker bars and wedges. The leaflet INDG317 adds felling cushions, pulp hooks, log tongs and high lift wedges.
Flip line: in the New Zealand code, a safety lanyard, also called a strop. It is an adjustable rope or strop used as a work positioning aid.
Friction device: a metal device that controls friction on a line. In a climbing system it lets the climber ascend, descend and work position (New Zealand code).
Friction hitch: a hitch, usually of synthetic fibre, that connects a climber to the climbing line and allows controlled movement (New Zealand code).

G to L

Grinder (stump grinder): portable machinery that reduces or removes stumps by grinding (New Zealand code).
Ground crew (groundie): the people working on the ground while a climber works in the tree. The New Zealand code says ground staff should be able to carry out an aerial rescue. The New South Wales code calls the person who controls the load the ground worker.
Hanger: a partly cut branch left in a tree. The New Zealand code says partially cut branches or hangers must not be left unsecured when work ends. The New Zealand forestry glossary calls a broken piece resting in a canopy a sailer.
Hinge: the wood the back cut leaves to hold the tree to the stump during its fall, so it guides the fall in the intended direction (OSHA 1910.266). The UK HSE lists the directional or sink cut, hinge and main felling or back cut as the parts that control a fell.
Hung tree (lodged tree): a tree leaning against another tree or object that stops it falling to the ground. Hung is the OSHA alternative for lodged. The UK HSE and the New South Wales code say hung up. The OSHA logging eTool calls lodged trees death traps and says to have them pushed or pulled down by a machine.
Kickback: when the top quarter of the saw bar touches something solid and the bar is flung backward into the operator. UGA calls that top quarter the kickback zone. The UK HSE defines it as the sudden uncontrolled upward and backward movement of the chain and guide bar towards the operator.
Kilonewton (kN): a unit of force used for the strength ratings of anchors and climbing gear. The New Zealand code says 1 kN is about 100 kilograms.
Lanyard: a flexible line of webbing or rope used to connect a harness to a lifeline or anchor point (Alberta OHS Code). A work positioning lanyard is a safety lanyard.

M to R

MEWP: the UK and New Zealand short name for a mobile platform that lifts workers. The UK HSE page on MEWPs says they give safe and quick access to trees and a secure working platform. Elsewhere the same kind of machine is an aerial device, or an EWP in Australia.
Notch: another word for the undercut, a cut that guides the direction of the fall (OSHA 1910.266). UGA writes about open-faced notches. The New South Wales code calls the two cuts that form it a scarf.
PPE: personal protective equipment. The New Zealand code covers safety helmets, leg protection for chainsaw users and safety footwear with toe caps.
Rigging: using ropes, slings and mechanical devices to lower limbs or sections of tree in a controlled way (New Zealand code).

S to Z

Safety mitt: a leather mitt attached to the front handle of a chainsaw. It protects the hand and keeps it on the handle in a kickback (New Zealand code).
Scarf: in the New South Wales code, two cuts made to form a notch that sets the direction of fall when felling or topping, or the direction of break when removing a branch. OSHA says undercut for the same notch.
Shock load: the dynamic load on a rope or rigging apparatus when a moving object or a falling person is stopped (New South Wales code).
Snag: in the US, any standing dead tree or part of one (OSHA 1910.266). The UK glossary uses it for something else: a stub of a cut or broken stem, branch or root that sticks out past a growing point.
Spikes (spurs, climbing irons, gaffs): climbing accessories fixed to the lower leg, used with a safety strop. The first three names come from the New Zealand code. The New South Wales code describes a pair of aids with gaffs or spikes, calf and foot supports, straps and pads.
Spring pole: a tree, limb or sapling under stress or tension from the weight or pressure of another object (OSHA 1910.266).
SRT: single rope technique. The UK HSE names it, with footlocking, as an example of rope access and positioning.
Strop: a word the New Zealand code uses for a safety lanyard, as in strop or flip line. It also uses it for a short line that holds a tool, the tool strop. The New South Wales code says tool lanyard or tool strop, which should incorporate a tear-away.
Stump jump: when the hinge fails and the tree detaches from the stump (UGA).
Tag line: a separate rope used during lowering to give more control over where the load lands (New South Wales code). More in rigging words by kind.
Throw line (throw bag): a weighted bag on a light line, thrown over an anchor point in the tree (New Zealand code).
Tree felling: making and placing the cuts to bring a standing tree to the ground. The New Zealand code says height reductions and structural or formative maintenance of standing trees are not felling.
Undercut: a notch cut in a tree to guide the direction of the fall and to prevent splitting or kickback (OSHA 1910.266).
Widowmaker: broken-off limbs hanging freely in the tree to be felled or in trees close by (OSHA logging eTool).
Work positioning: the UK HSE gives changeover climbing with a harness, friction knot and climbing line as an example. Alberta defines a work positioning system as PPE attached to a vertical safety line. The New Zealand code says a work positioning harness is not suitable for fall arrest.

Pruning words

Pruning words move between countries more than felling words do, and some change meaning on the way. The sources here are a January 1994 paper in Arboriculture and Urban Forestry by Richard Harris and a UK glossary that says it includes extracts from a 1999 government publication. Both are older than the safety codes above.

Word	What the source says	Source
Crown cleaning	Removal of dead, dying, diseased, crowded, weakly attached or low-vigor branches and watersprouts	1994 paper
Crown thinning	Crown cleaning plus selective thinning for light and air. The UK glossary says removal of a share of the secondary branch growth to even out foliage	1994 paper; UK glossary
Crown raising	Removing the lower branches for clearance of buildings, vehicles or people	1994 paper
Crown lifting	The UK word: removal of limbs and small branches to a set height above ground	UK glossary
Crown reduction	Reducing the height or spread of a tree. The paper also says crown shaping	1994 paper
Thinning cut, heading cut	Thinning removes a branch at its origin or cuts to a lateral large enough to take over. Heading cuts to a bud, a stub or a lateral too small to take over	1994 paper
Topping	The paper says heavy heading led to the terms topping, stubbing, hat-racking and rounding-over. The New South Wales code uses topping for something else: removing the upper canopy in one operation by felling while aloft	1994 paper; NSW code
Pollarding	The paper calls it a training system where shoots are cut back to the same height each time and knobs form. The UK glossary says removal of the canopy back to the stem or primary branches	1994 paper; UK glossary
Flush-cut	A pruning cut that removes part of the branch bark ridge or branch collar	UK glossary
Lions tailing	A branch with few side branches except at its end, liable to snap from end loading	UK glossary

So topping can mean a bad pruning practice in one source and a felling method in another. The word alone does not say which.