c.1600, "made more dense," past participle adjective from condense. Of literary works, from 1823. Condensed milk attested by 1863.
early 15c., from Middle French condenser (14c.) or directly from Latin condensare "to make dense," from com-, intensive prefix (see com-), + densare "make thick," from densus "dense, thick, crowded," a word used of crowds, darkness, clouds, etc. (see dense).