- solid (adj.)
- 1391, from O.Fr. solide "firm, dense, compact," from L. solidus "firm, whole, entire" (related to salvus "safe"), from PIE base *sol- "whole" (cf. Gk. holos "whole," L. salus "health;" see safe (adj.)). Slang sense of "wonderful, remarkable" first attested 1920 among jazz musicians. The noun is recorded from 1495. Solid South in U.S. political history is attested from 1858. Solidify is from 1799 (trans.), 1837 (intrans.). Solid state as a term in physics is recorded from 1953; meaning "employing transistors (as opposed to vacuum tubes)" is from 1959.