Glossary A

Aboard
On or within the boat.

Abseil
The process by which a climber can descend a fixed rope. Also known as Rappel.

Acclimate
The adaptation of an organism to environmental changes.

Accretion
The accumulation of sediment (mud, sand, etc.) by deposition, often occurring along a shoreline or in a river delta.

Adamantine
Having a luster like that of a diamond.

Adipose Fin
A small fin between the dorsal and tail fin.

Adrift
Floating free with the currents and tide, not under control.

Adze
A thin blade mounted perpendicular to the handle on an ice axe that can be used for chopping footholds.

Affluent
A stream or river that flows into a larger one; a Tributary.

Aftershock
Small earthquakes that occur after a large earthquake.

A-frame
A basic tent shape, the cross section of which resembles an "A".

Airfall
(Also called ashfall) Volcanic ash that falls from an ashcloud or a volcanic column.

Alcove
A belay ledge that is surrounded by vertical rock on all sides.

Alloy
An alloy is a combination of two or more metals.

Alluvial
Deposited by running water.

Altimeter
An instrument that measures elevation by using barometric (air) pressure.

Altitude
The height above sea level.

Altitude sickness
A medical condition that is often observed at high altitudes. Also known as Acute mountain sickness, or AMS.

Amidships
In the middle of the ship

Andesite
A type of volcanic rock. This gray to black rock is composed of about 54 to 62 percent silica, plus some iron and magnesium.

Anemometer
A device that measures wind velocity.

Anorak
A pullover jacket. Anoraks are practical because there is no zipper running top to bottom that can fail or let your body warmth escape when moving.

Arbalest
A medieval crossbow that needed a windlass to draw the bowstring back.

Archipelago
A group or chain of islands clustered together in a sea or ocean.

Arrow fletcher
Tool used to precisely aligned feathers or vanes that are being glued to an arrow during manufacturing.

Arrowsmith
A person who makes metal arrowheads.

Ascham
A tall narrow cabinet in which bows and arrows are kept.

Ashfall
(Also called airfall) Volcanic ash that falls from an ashcloud or a volcanic column.

Astern
Behind the boat

Atoll
A ring (or partial ring) of coral that forms an island in an ocean or sea.

Auger
A carpenter's tool boat builders use for boring holes in wood.

Avalanche
A large mass of falling and / or sliding material. Avalanches can be composed of rock, snow, soil, or ice.

Azimuth
Same as bearing. Refers to the degree of bearing from your current position to a landmark or destination. Reversing the bearing would be known as a back azimuth or back bearing.