'Supple' is Latin for 'bending under' — from 'supplex' (kneeling). Kin to 'supplicate.'
Bending and moving easily and gracefully; flexible; not stiff or rigid.
From Old French souple, from Latin supplex (bending the knee, humbly submissive), a compound of sub- (under) + plicare (to fold, to bend). The verb plicare derives from Proto-Indo-European *pleḱ- (to plait, to fold, to weave), a root of remarkable fertility: it generated Latin plectere (to plait), plicare, and their compounds duplicare (to double), explicare (to unfold), implicare (to entangle), replicare (to fold back). Greek cognates include