1553, from Gk. phalanx (gen. phalangos) "line of battle, battle array," also "finger or toe bone," originally "round piece of wood, trunk, log," of unknown origin, perhaps from PIE base *bhelg- "plank, beam" (cf. O.E. balca "balk;" see balk). In anatomy, originally the whole row of finger joints, which fit together like infantry in close order. Fig. sense of "number of persons banded together in a common cause" is attested from 1600 (cf. Sp. Falangist, member of a fascist organization founded in 1933).