What is the origin of amphibious?
Amphibious and amphibian have several overlapping meanings in zoology and botany, but in the sense “relating to combined military operations by land and naval forces against a common target,” only amphibious is used. In the mid-1930s, at a time when air power was rapidly developing, the neologisms triphibian and triphibious were coined very useful for describing combined land, sea, and air operations, but an abomination—two abominations, even, for purists. Amphibious ultimately comes from Greek amphíbios “having a double life,” used by science writers about frogs and plants. In later Greek the Neoplatonist philosopher Plotinus used amphíbios metaphorically to describe the human soul as an inhabitant of two worlds. Amphíbios is composed of two very common Proto-Indo-European roots, ambhi– “on both sides, around” and gweiə-, gwey-, gwī-, gwi– (with many other variants) “to live.” Ambhi– becomes amphí in Greek, as in amphithéātron “amphitheater,” literally, “a place for watching from both sides.” Ambhi– becomes amb(i)– in Latin, a prefix meaning “around, both..,” as in ambiguus “unsettled, undecided.” \ The Greek combining form bio– comes from bíos “life,” from Proto-Indo-European gwios (gw– becomes b– in Greek under certain conditions). The root variant gwī– is the source of Latin vīta “life.” Amphibious entered English in the 17th century.