- aberration
- aberrometer
- abeyance
- abiatrophy
- abient
- abiology
- abiosis
- abiotrophy
- abirritation
- abiuret
- ablactation
- ablate
- ablatio placentae
- ablatio retinae
- ablepharia
- ablepsia
- ablution
- abnormal growth
- abocclusion
- aboiement
- aborad
- aboral
- abortifacient
- abortion
- abortive
- abrade
- abrosia
- abscess
- abscission
- absence
- absolute amenorrhea
- absolute hemianopia
- absolute strabismus
- absorbefacient
- absorption spectrometer
- abstergent
- abstinence symptom
- abterminal
- abulia
- acantheceous
- acanthion
- acantholysis
- acanthopelvis
- acanthotic
- acapnia
- acardiac monster
- acariasis
- acarina
- acarus
- acatamathesia
- accelerans
- abrasion
- abruptio placentae
- absinthe
- absolute diet
- absolute error
- absorptionchromatography
- acantha
- acarid
- acatalasia
- acatharcia
- acceleration
- accessory sign
- accessory thyroid
- accessorynerve
- accident prevention
- accidental abortion
- acciimation
- accommodation iridoplegia
- accouchement
- accoucheuse
- acceptor
- accidental death
- accidental parasite
- accipitotemporal sulcus
- accommodometer
- accompanying vein
- accordion abdomen
- accritic
- accumulation disease
- accurate reading
- acenesthesia
- acephalocyst
- acephalus
- acervuluscerebral
- acetabular artery
- acetarsol
- acetoacetic acid
- acetohexamide
- acetone ahcohol
- acetonuria
- achievement quotient
- Achillestendon
- achillobursiti
- achlys
- acholia
- achondroplasia
- achordate
- achrestic
- achromasia