"made up of distinct parts or elements," c. 1400, from Old French composite, from Latin compositus "placed together," past participle of componere "to put together, to collect a whole from several parts," from com "with, together" (see com-) + ponere "to place" (past participle positus; see position (n.)).
The noun, "something made up of two or more different parts or elements," is attested from late 14c. in reference to numbers. Composite number "number that can be measured exactly by a number more than one" is from 1730 (in Middle English, with French word-order, nombrys composyt, c. 1400). A composite photograph (1884) is one printed from more than one negative.