1.Definition: (used of verbs) having standard (or regular) inflection
2.Definition: (used of vowels or syllables) pronounced with little or no stress
"A weak stress on the second syllable"
3.Definition: deficient in intelligence or mental power
"A weak mind"
4.Definition: deficient in magnitude; barely perceptible; lacking clarity or brightness or loudness etc
"Weak colors", "A weak pulse"
5.Definition: deficient or lacking in some skill
"He's weak in spelling"
6.Definition: lacking bodily or muscular strength or vitality
7.Definition: likely to fail under stress or pressure
"The weak link in the chain"
8.Definition: not having authority, political strength, or governing power
"A weak president"
10.Definition: tending downward in price
"A weak market for oil stocks"
11.Definition: wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings
12.Definition: wanting in physical strength
"A weak pillar"