1888 in geology, from Greek allogenes "of another race, stranger," from allos "other, another, different" (see allo-) + -genes "born" (see -gen) + -ic. An earlier adjective was allogeneous "of a different kind or nature" (1842).
all-nighter
allo-
allocate
allocation
allocentric
allogenic
allograph
allons
allonym
allopath
allopathic