1. Lacking strength; SYN. nerveless.
2. Pathetically lacking in force or effectiveness; SYN. lame.

Stupid; pertaining to idiocy.

ETYM Latin infirmus: cf. French infirme. Related to In- not, and Firm.
Lacking firmness of will or character or purpose.

ETYM Latin stupidus, from stupere to be stupefied: cf. French stupide.
Lacking or marked by lack of intellectual acuity.

(Homonym: week).
1. Lacking physical strength or vigor.
2. Having little physical or spiritual strength.
3. (Grammar) Used of verbs having standard (or regular) inflection.

ETYM From Joannes Duns Scotus, a schoolman called the Subtle Doctor, who died in 1308. Originally in the phrase. Related to Note below.
These words are used to express a low opinion of someone's intelligence; SYN. dunderhead, numskull, blockhead, bonehead, lunkhead, hammerhead, knucklehead, loggerhead, muttonhead.

Jerk