lymph (n.)

1640s, from Modern Latin lymphaticus "pertaining to the lymph," from Latin lympha (see lymph). The English word also sometimes is used in what was the primary sense of lymphaticus in classical Latin, "mad, frenzied." OED reports this meaning "difficult to account for," but perhaps due to association of lympha with nymphe; compare Greek nymphian "to be frenzy-stricken." Also sometimes in reference to the appearance or temperament of one thought to suffer from excess of lymph, "dull, sluggish, slow in thought or action, with flabby muscles and pale skin" (1834).

c. 1600, from French limpide (15c.) and directly from Latin limpidus "clear, transparent" (source also of Spanish límpido, Italian limpido), related to limpor "a clear liquid," limpa "water goddess, water," which is perhaps cognate with lympha "clear liquid" (see lymph). Related: Limpidly.