- aberrancy
- aberrant
- abiogenesis
- abiogenetic
- abiogenous
- abiogeny
- abort
- aborted
- aberrance
- abiogenetically
- abortion
- abortive
- abortiveness
- accelerator
- actinomorphous
- activate
- acquire
- actinomorphic
- adnate
- afferent
- agamic
- agamous
- air-bladder
- amylopsin
- anabolic
- analogic
- analogical
- anaphase
- anarthrous
- anabiosis
- anabolism
- analogy
- anamorphosis
- apatetic
- apparatus
- appendiculate
- aster
- atavistic
- armature
- asexual
- asexuality
- atavism
- armour
- association
- autochthones
- autogamous
- autogenous
- autogeny
- autolysis
- autochthon