Etymology
1. O.E.
frogga, a dim. of
frox, forsc, frosc "frog," from P.Gmc.
*fruska-z (cf. O.N.
froskr, M.Du.
vorsc, Ger.
Frosch "frog"), probably lit. "hopper" (cf. Skt.
provate "hops," Rus.
prygat "to hop, jump"). The L. word (
rana) is imitative of croaking. As a derogatory term for "Frenchman," 1778 (short for
frog-eater), but before that (1652) it meant "Dutch" (from
frog-land "marshy land"). To have a
frog in the throat "hoarseness" is from 1909.
Frogman "scuba diver in rubber suit" is from 1945.
Frog-march (1871) originated among London police and referred to their method of moving "a drunken or refractory prisoner" by carrying him face-down between four people, each holding a limb; the connection with
frog perhaps being the notion of going along belly-down. By the 1930s, the verb was used in ref. to the much more efficient (but less frog-like) method of getting someone in an arm-behind-the-back hold and hustling him or her along like that.
2. From Middle English frogge, from Old English frocga, from Proto-West Germanic *froggō (“frog”). Cognate with Old Norse frauki, and Old English frox, frosc, whence Modern English frosh and frosk (“frog”).
3. Possibly related to Saterland Frisian Poage (“frog”), German Low German Pogg, Pogge (“frog”).
4. Sense 5 (organ on a horse's hoof) is a calque of Ancient Greek βάτραχος (bátrakhos). See: English '
frosh', Frisian, Saterlandic 'Poage'.