"period of unrestrained activity," 1887, American English, perhaps via intermediate sense of "as much drink as a man can hold" (1670s), from earlier meaning "load of hay or wood" (1590s), of unknown origin. Used in U.S. colloquial speech from 1834 to mean "a quantity, a lot."
"slash or rend in a garment," c.1400, of unknown origin.
[1887+; fr jag, ''a load,'' found by 1597, whence ''as much liquor as a man can drink,'' found by 1678]
A Jaguar automobile (1950s+)