An Encylopedia Britannica Company

weak

weak /ˈwiːk/ adjective
weaker; weakest
weak
/ˈwiːk/
adjective
weaker; weakest
Britannica Dictionary definition of WEAK
[also more weak; most weak]
: having little physical power or ability : not strong
: having little power or force
: likely to break or stop working properly : not able to handle weight, pressure, or strain
disapproving
: having little power or influence
: not able to make good decisions or deal with difficult situations
: lacking enough or the usual amount of an important ingredient
: not powerful in action or effect
: not likely to persuade or convince people that something is true, real, correct, etc.
: not having enough skill or ability
: failing to produce the result that is wanted : not effective
: showing little confidence or enthusiasm
10 
: having a value that is small or is not increasing : less valuable
: in a poor financial condition
11 
: dull or pale
12 
: smaller than the usual size
13 
grammar : following the normal patterns by which the past tenses of verbs are usually formed : regular

a weak stomach

see 1stomach

the spirit is willing but the flesh is weak

see 1spirit

weak at/in the knees

: so nervous or powerfully affected that it is difficult for you to stand
weak, feeble, and frail mean lacking strength.
weak is a general word that can describe either a temporary or permanent lack of strength.
feeble stresses the kind of very great weakness that often makes other people feel pity or sympathy.
frail is usually used to describe a very weak person who is easily injured especially because of illness or age.