- Apodiformes
- Amphipoda
- Anguilliformes
- Anacanthini
- Anostraca
- Aplacophora
- Actinomyxidia
- Amoebina
- Araneida
- Artiodactyla
- Anoplura
- Alcyonacea
- Acarina
- anti b
- anti infective factor
- anti pernicious principle anaemia principle
- anti a
- anticoagulation
- allopathy
- aftercare
- a station
- a compound wherein the members if uncompounded would be in the same case and connected by the conjunction 'and' (as
- assemblies of god
- assembling time
- assembling phase
- agglomerative
- aerophilately
- armamentarium
- art collection
- accumulations
- asselar skull
- archiving
- anthologize
- Audubon's warbler
- Audubon warbler
- aland islands
- aspargine
- arginine
- acetylchloride
- aminoformic acid
- acetylcoenzyme a
- adrenaline apnoea
- amino resin
- aminoplast
- anticpative
- anticoagulant bridge
- antienzyme
- a mass
- abradant
- Arctium minus