"one who or that which condenses," 1680s, agent noun from condense. Given a wide variety of technical uses in late 18c. and 19c.
big spotted cat of the Americas (Felis onca), c. 1600, from Portuguese jaguar, from Tupi jaguara, said in old sources to denote any large beast of prey ["tygers and dogs," in Cullen's translation of Abbe Clavigero's "History of Mexico"]. Compare Tupi jacare "alligator." As a type of stylish British-made car from 1935; in this sense the abbreviation Jag is attested by 1951.
early 15c., "thicken, make more dense or compact" (implied in condensed), from Old French condenser (14c.) or directly from Latin condensare "to make dense," from assimilated form of com-, here perhaps an intensive prefix (see com-), + densare "make thick," from densus "dense, thick, crowded," a word used of crowds, darkness, clouds, etc. (see dense).
Sense in chemistry and physics, "to reduce to another and denser form" (as a gas or vapor to a liquid) is from 1660s. Intransitive sense "become denser" is from 1650s. Related: Condensed; condensing.