This word made me laugh because it sounds like it means “something that is extremely jacent.” Unfortunately, superjacent isn’t nearly that interesting; it just means “lying above”, like adjacent means “lying next to”.

Here’s what is interesting, though: jacent is actually a word by itself. Weird, huh? It means “lying at length”, as in “the jacent posture.” It comes from the Latin word jacere, which means “to lie” or “rest”.

So, just slap on a random prefix like ad- or super- and you have a new word! Merriam-Webster also mentions the words subjacent, “lying below”, and circumjacent, “surrounding”. I also discovered interjacent, “between or among others”.

But there’s no such thing as transjacent, prejacent, postjacent, cojacent, or nonjacent (though nonadjacent is actually a word). Can you think of any others?