early 14c., from Middle Dutch splinter, splenter "a splinter," related to splinte (see splint). The adjective (in splinter party, etc.) is first recorded 1935, from the noun.
1580s (transitive), from splinter (n.). Figurative sense from c. 1600. Intransitive use from 1620s. Middle English had splinder (v.) "to shatter" (of a spear, etc.), mid-15c. Related: Splintered; splintering.