c. 1600, "freedom from suffering, passionless existence," from French apathie (16c.), from Latin apathia, from Greek apatheia "freedom from suffering, impassibility, want of sensation," from apathes "without feeling, without suffering or having suffered," from a- "without" (see a- (3)) + pathos "emotion, feeling, suffering" (from PIE root *kwent(h)- "to suffer"). Originally a positive quality; sense of "indolence of mind, indifference to what should excite" is by 1733.
Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).
In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.
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Definitions of apathetic from WordNet
showing little or no emotion or animation;
a woman who became active rather than apathetic as she grew older
marked by a lack of interest; "the universe is neither hostile nor friendly; it is simply indifferent";