"to set aside for a special purpose," 1630s, from Medieval Latin allocate (the common first word of writs authorizing payment), imperative plural of allocare "allocate, allot," from Latin ad "to" (see ad-) + locare "to place," from locus "a place" (see locus). It is a twin of allow. Related: Allocated; allocating. English allocate as an adjective from mid-15c. in legal use.