Dinky

google

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late 18th century: from Scots and northern English dialect dink ‘neat, trim’, of unknown origin.

wiktionary

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1780-90; compare Scots dink(“neatly dressed, trim”) (of obscure origin); sense shift perhaps: trim > dainty > small > insignificant; +‎ -y.

cf. DINK

etymonline

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dinky (adj.)

1788, dinkie, "neat, trim, dainty, small," from Scottish dialectal dink "finely dressed, trim" (c. 1500), which is of unknown origin. Modern sense of "small, tiny" is by 1859. Related: Dinkiness.