quirk (n.)

1560s, "a quibble, an artful evasion," a word of unknown origin, perhaps connected to German quer (see queer (adj.)) via the notion of twisting and slanting; but its earliest appearance in western England dialect seems to argue against this as its source. Perhaps originally a technical term for a twist or flourish in weaving. Sense of "peculiarity" is c. 1600.

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Definitions of quirk from WordNet
quirk (n.)
a strange attitude or habit;
Synonyms: oddity / queerness / quirkiness / crotchet
quirk (n.)
a narrow groove beside a beading;
quirk (v.)
twist or curve abruptly;
She quirked her head in a peculiar way