1802, from Mod.L.
unilateralis, from
unum, neut. of
unus "one" (see
one) +
latus (gen.
lateralis) "side" (see
oblate (n.)). Jeremy Bentham (1748-1832) may have been the first to use it in the legal sense of "made or entered into by one party."
Unilateral disarmament is recorded from 1929.
Unilateralism is recorded from 1926, and seems to have been used in the sense of "advocate of unilateral disarmament." Meaning "pursuit of a foreign policy without allies" is attested from 1964.
"It is useless for the sheep to pass resolutions in favor of vegetarianism, while the wolf remains of a different opinion." [William Ralph Inge, "Outspoken Essays," 1919]