1.
Asteroid a small celestial body composed of rock and metal
2.
Astrolabe instrument used to calculate positions of celestial bodies
3.
Astrology divination by the positions of the planets and sun and moon
4.
Astrophysics the study of the properties of celestial bodies
5.
Astrophysicist a scientist who studies the properties of celestial bodies
6.
Astronaut a person trained to travel in a spacecraft
7.
Astronomer a physicist who studies celestial bodies and the universe
8.
Astronomy the branch of physics that studies celestial bodies
9.
Astronomical relating to the branch of physics studying celestial bodies
10.
Astrobiology the study of living organism throughout the universe
11.
Astrobiologist an expert on the study of life in the universe
12.
Audible heard or perceptible by the ear
13.
Audience a gathering of spectators or listeners at a performance
14.
Audio a transmitted signal you can hear
15.
Audiovisual involving both hearing and seeing
16.
Audit attend academic courses without getting credit
17.
Audition a test of the suitability of a performer
18.
Auditor a qualified accountant who inspects accounting records
19.
Auditorium the area of a theater or hall where the audience sits
20.
Auditory of or relating to the process of hearing
21.
Inaudible impossible to hear; imperceptible by the ear
22.
Amphibious operating or living on land and in water
23.
Antibiotic a substance used to kill microorganisms and cure infections
24.
Biodegradable capable of being decomposed
25.
Biodiversity the variety of plant and animal life in a habitat
26.
Biography an account of the series of events making up a person's life
27.
Biohazard danger to humans or the environment from an infectious agent
28.
Biology characteristic life processes of living organisms
29.
Biomass the total amount of living matter in a given unit area
30.
Biome major ecological community with distinct climate and flora
31.
Bionic having one or more electromechanical body parts
32.
Biopsy the removal and examination of tissue from a living body
33.
Biosphere the regions of the Earth where living organisms exist
34.
Biotic of or relating to living organisms
35.
Microbiology the study of very small forms of life
36.
Symbiosis the relation between two interdependent species of organisms
