- lacking some essential; incomplete; defective
- inadequate in quantity or supply; insufficient
WordReference Random House Learner's Dictionary of American English © 2026
de•fi•cient /dɪˈfɪʃənt/USA pronunciation
adj.
WordReference Random House Unabridged Dictionary of American English © 2026- relating to or marked by deficiency:deficient in math skills.
de•fi•cient
(di fish′ənt),USA pronunciation adj.
n.
de•fi′cient•ly, adv.
- lacking some element or characteristic;
defective:deficient in taste. - insufficient;
inadequate:deficient knowledge.
n.
- a person who is deficient, esp. one who is mentally defective.
- Latin dēficient- (stem of dēficiēns, present participle of dēficere to fail, run short, lack, weaken), equivalent. to dē- de- + fic-, combining form of facere to make, do1 + thematic -i- + -ent- -ent
- 1575–85
Collins Concise English Dictionary © HarperCollins Publishers::
deficient /dɪˈfɪʃənt/ adj
'deficient' also found in these entries (note: many are not synonyms or translations):
albino
- cripple
- defect
- deficiency
- immature
- imperfect
- inferiority complex
- insufficient
- lack
- lime
- make-up
- MD
- meagre
- out
- poor
- putrid
- short
- want
- abundant number
- anadenia
- antihemophilic factor
- bad
- balance
- challenged
- civil
- defective
- defective number
- deficient number
- deficit
- destitute
- fail
- hearing-impaired
- hypothyroidism
- impaired
- incompetent
- incurious
- indigent
- insensitive
- invalid
- irreverent
- jejune
- lacking
- marl
- meager
- myatonia
- numb
- oaf
- pallid
- perfect number
- purblind