There’s a diplosaurus in your disk drive.
Dear Word Detective: Talking with my family some time ago, we somehow got to the subject of those ‘X-off’ combinations which seem to have become fairly commonplace in recent years. You know, “dance-off,” “sing-off,” “rap-off,” “nerd-off,” what have you — it appears that any sort of competitive confrontation can be fit into that mold. So we got to wondering where it all started. Thinking of it a bit, I guess it makes sense that it would stem from “face-off” (Oxford Concise: “ a direct confrontation.  [Ice Hockey] the start of play.”), but the more I think about it the more I’m puzzled by the word “off,” there. I mean, you have two teams facing each other, that seems clear, but why are they facing OFF? I know that adverbs can be kinda arbitrary, so there might not be an answer for that. Still, it bugs me. I’d appreciate any insight you might offer on that subject. — Yael.
There’s a “nerd-off”? Does it involve fixing computers while reciting the names of obscure dinosaurs? Speaking of prehistoric trivia, does anyone else see the term “face-off” and immediately think of the 1997 John Travolta/Nicholas Cage movie? No? You’re lucky. For the life of me, I can’t imagine what compelled me to see that nonsensical schlock-fest (starring my two least-favorite actors), but something did, and I still, obviously, bear the scars.
“Off” is a daunting word with a dizzying array of uses. It began as an emphatic form of the preposition “of,” which in Middle English carried the sense of “from, or out of,” in the way we might say that a person is “Mr. Edwards of London.” The form “off” gradually took on a stronger meaning than “of,” connoting “away, away from” (e.g., “drive off”) or “at a distance from” (“off the coast of France”). By the early 18th century the two words had completely separated and “off” came to be used not only as a preposition but an adjective, adverb and noun as well.
“Off” in modern English carries those senses of motion, direction or distance from a place, thing or person, but it also is used to express resistance to motion towards a place, thing, etc., as in “ward off” or “keep off.” In “dance-off,” bake-off,” etc., we’re seeing a verbal phrase used as a noun, with the “off” signifying resistance in the form of confrontation or competition. The earliest use of this sense seems to have been in “face-off,” appearing in 1889 and originally meaning the moment in a game of ice hockey or lacrosse when play is started by dropping or placing the puck or ball between two opposing players who are literally facing each other. It wasn’t until the 1950s that “face-off” came into use in the more general sense of “direct confrontation.” (In that awful Cage/Travolta movie, the confrontation between the two involved actually swapping faces. Yeah, it was that stupid.)
Meanwhile, a slightly different sense of “off” had been dumped into the mix. In 1870 the phrasal noun “play-off” first appeared in print meaning a game played to decide a tie at the end of a previous game (“The tie game of yesterday was played off to-day,” 1880). This “play-off” invoked a very old sense of “off” meaning “exhaust or finish completely” (as in our modern “finish off”). It wasn’t until 1932 that “play-off” came to mean (first in the US, of course) “a series of games, matches, or contests played to decide a championship, competition, etc.” (Oxford English Dictionary).
The precedents of “face-off” and “play-off” subsequently served as models for all the little “X-offs” you’ve noticed, from “cook-off” (1936) to “bake-off” (1949) to the more recent “dance-off,” “sing-off,” etc. These terms all employ both the “confrontation or contest” sense and the “finish” sense (in that there is only one winner) of “off.”