1630s, "having two modes of existence; of doubtful nature," from Greek amphibia, neuter plural of amphibios "living a double life," from amphi "of both kinds" (see amphi-) + bios "life," from PIE root *gwei- "to live."
Formerly used by zoologists to describe any sort of animal at home on land and in the water, including crocodiles, walruses, beavers, seals, hippopotami; the restriction to the class of animals between fishes and reptiles with life cycles that begin in water and mature on land is from 1835; Amphibia has been used a zoological classification in this sense since 1788.
1610s, "a cutting off of tree branches, a pruning," also "operation of cutting off a limb, etc., of a body," from French amputation or directly from Latin amputationem (nominative amputatio), noun of action from past-participle stem of amputare "to cut off, lop off; cut around, to prune," from am(bi)- "around" (from PIE root *ambhi- "around") + putare "to prune, trim" (from PIE root *pau- (2) "to cut, strike, stamp").
