deficient
Short of adequate
Deficient means lacking something necessary or falling short of a standard.
A diet deficient in vitamins is missing essential nutrients.
A deficient immune system doesn't function properly.
The word often appears in technical or formal contexts: mentally deficient, oxygen-deficient environments.
Something deficient is inadequate for its purpose—not just less than ideal, but meaningfully incomplete.
Below acceptable quality
- inferiorOf lower rank
- substandardBelow required quality
- unsatisfactoryNot good enough
- lackingBeing without something
wanting · flawed · imperfect · defective · incomplete · mediocre · poor · weak
Being without something
- missingNot present, whereabouts unknown
- devoidEntirely without
- voidWithout legal effect
- bereftDeprived through loss
empty · without · deprived · stripped · bare · barren · depleted · drained
Lacking proper nutrition
- undernourishedInsufficiently nourished
- anemicDeficient in vigor
- nutrient-poorLow in essential compounds
- underfedLacking adequate food
starved · fasting · dietary · supplementation · fortified · RDA · bioavailability
Weakened in function
- challengedDisputed or questioned
- delayedMade to wait longer
- disabledMade unable to function
- handicappedHaving imposed disadvantage
subpar
Below acceptable quality
- inferiorOf lower rank
- substandardBelow required quality
- unsatisfactoryNot good enough
lacking · wanting · flawed · imperfect · defective · incomplete · mediocre · poor · weak · unacceptable
lacking
Being without something
bereft · empty · without · deprived · stripped · bare · barren · depleted · drained · exhausted
malnourished
Lacking proper nutrition
- undernourishedInsufficiently nourished
- anemicDeficient in vigor
- nutrient-poorLow in essential compounds
underfed · starved · fasting · dietary · supplementation · fortified · RDA · bioavailability
impaired
Weakened in function
- challengedDisputed or questioned
- delayedMade to wait longer
- disabledMade unable to function
handicapped · learning-disabled · remedial · struggling · underperforming
- nutrition termscalorie, high protein, balance, low-fat, low fat
- academic failurefailing grade, failed test, F grade, flunk, flunking
- incompleteincomplete, unfinished, partial, fragmentary, half-done
- scarcityscarcity, scarce, shortage, scant, scanty
- falling shortlacking, shortfall, failure, gap, inferior
- inferiorinferior, substandard, second-rate, second-class, subpar
deficientperfect
Without any flaw
flawless · faultless · satisfactory · sound · acceptable
- vitamin D deficiencyInadequate sunshine hormone levels
- acquired immune deficiency syndromeHIV-caused immune failure
- iron deficiencyInsufficient bodily ferritin levels
- vitamin deficiencyInsufficient essential micronutrients
- immune deficiencyImpaired protective system function
- vitamin A deficiencyInadequate retinol levels