If you hear your Unionville High School student using the adjective "nifty," you can thank the Young Relative. At dinner on Sunday he used it, quite aptly, to describe an especially neat solution to a crossword puzzle and then explained that "nifty" has been on frequent rotation in his vocabulary playlist recently.
I looked up the word's origin on "Online Etymology Dictionary" and found that "nifty" first appeared in the middle of the 19th century, "perhaps theatrical slang, first attested in a poem by Bret Harte, who said it was a shortened, altered form of magnificat."
By the way, the Young Relative said he is looking forward to running outside again after a winter of competing indoors. Although he enjoyed the track team's road trips to various colleges with indoor facilities, he much prefers the fresh air.