- afferent influx
- axodendrosomaic synapse
- atlas mountains
- axonal nervous condition
- axon hillock
- axon reflex
- axonotmesis
- axotomy
- ayraes tube
- ayerzas disease
- angussmith varnish
- arius
- arithmophobia
- Augustinian Hermits
- augustinian canons
- Annamese
- Annamite
- affright
- an authoritarianist
- auto bypass
- autoanalyser
- an autobiography
- autoagglutinating phenomenon
- autoimmune vasculitis
- astraphobia
- aquaphobia
- acrophobia
- algophobia
- autonomic centre
- autonomic drug
- anpu
- ansa cervicalis
- autosite
- autosomal chromosome
- autoprothrombin
- auxillary tail
- avascualarization
- aide memoire
- aide
- antitumor
- antineoplastic
- antincrustor
- average information content
- amebous
- astronautical
- alkylating agent
- antimetabolite
- antineuritic factor
- an assertion
- aeronausiphobia