snaggle-toothed adj.

1570s, "stump of a tree, branch," a word of Scandinavian origin; compare Old Norse snagi "clothes peg," snaga "a kind of ax," snag-hyrndr "with sharp points" ("snag-cornered"). The connecting notion seems to be "sharp protuberance, projecting point."

The general meaning, in reference to any sharp or jagged projection is recorded from 1580s; especially "tree or part of a tree in water and partly near the surface, so as to be dangerous to navigation" (1807). The figurative meaning "hidden obstacle, unexpected impediment" is from 1829.

Old English toð (plural teð), from Proto-Germanic *tanthu- (source also of Old Saxon, Danish, Swedish, Dutch tand, Old Norse tönn, Old Frisian toth, Old High German zand, German Zahn, Gothic tunþus), from PIE root *dent- "tooth." Plural teeth is an instance of i-mutation.

The loss of -n- before spirants is regular in Old English, Old Frisian, and Old Saxon: compare goose (n.), five, mouth (n.). Also thought, from stem of think; couth from the stem of can (v.1); us from *uns.

Application to tooth-like parts of other objects (saws, combs, etc.) first recorded 1520s. Tooth and nail as weapons is from 1530s. The tooth-fairy is attested from 1964.