"full of cracks or fissures," 1640s, from chink (n.1) + -y (2). As a noun by 1879, variant of chink (n.2), derogatory term for "Chinese person;" chiefly British.
Entries linking to chinky
chink n.1
"a split, crack," 1530s, with unetymological -k + Middle English chine (and replacing this word) "fissure, narrow valley," from Old English cinu, cine "fissure," which is related to cinan "to crack, split, gape," from Proto-Germanic *kino-(source also of Old Saxon and Old High German kinan, Gothic uskeinan, German keimen "to germinate;" Middle Dutch kene, Old Saxon kin, German Keim "germ"). The connection being in the notion of bursting open.
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.
Chink n.2
"a Chinese person," 1901, derogatory, perhaps derived somehow from China, or else from chink (n.1) with reference to eye shape.