after a character in Daniel Defoe's novel Robinson Crusoe (1719)
man Friday in American English
see Friday (sense 2)
man Friday in American English
noun
a male assistant to an administrator or executive; right-hand man
Word origin
[1885–90; after Friday, the devoted servant in Robinson Crusoe]This word is first recorded in the period 1885–90. Other words that entered Englishat around the same time include: classified, lineup, reactor, retread, twofer