Etymology
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helpless (adj.)
"unable to act for oneself," c. 1200, from help (n.) + -less. Related: Helplessly; helplessness. In Middle English and later sometimes "unable to give help, affording no help" (late 14c.), but this never was common.
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imbecility (n.)

early 15c., imbecilite, "physical weakness, feebleness (of a body part), impotence," from Old French imbécillité and directly from Latin imbecillitatem (nominative imbecillitas) "weakness, feebleness, helplessness," from imbecillus "weak, feeble," of uncertain origin (see imbecile). "Weakness in mind" (as opposed to body) was a secondary sense in Latin but was not attested in English until 1620s.

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basket case (n.)
1919, American English, originally a reference to rumors of quadriplegics as a result of catastrophic wounds suffered in World War I (the U.S. military authorities vehemently denied there were any such in its hospitals), from basket (n.) + case (n.2). Probably literal, i.e., stuck in a basket, but basket had colloquial connotations of poverty (begging) and helplessness long before this. Figurative sense of "person emotionally unable to cope" is from 1921.
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