helpless

Helpless is a synonym of weak.

As adjectives the difference between weak and helpless

is that weak is lacking in force (usually strength) or ability while helpless is unable to defend oneself or to act without help.

As adjectives the difference between helpless and hapless

is that helpless is unable to defend oneself or to act without help while hapless is very unlucky; ill-fated.

As an adjective helpless

is unable to defend oneself or to act without help.

As a noun altrices is

nursers; those birds whose young are hatched in a very immature and helpless condition, so as to require the care of their parents for some time.