It occurred to me today that I had no word for the opposite of ‘nocturnal.’ I had to look it up. Since nocturnal is a very common word that most people learn in elementary school science, I found it weird that the word ‘diurnal’* (awake/active in the day) is so rare - I can’t recall hearing it before, at least.
Now I’m interested to see if there are many other examples of words like this.
*also interesting: crepuscular, which means active at twilight.
I suspect there will be quite a list of words that have built-in negation, where removal of the negation prefix doesntbrender the modern English opposite.
For example, disappoint. ‘Appoint’ is a common word, but doesn’t mean the opposite, and in this case, there are probably at least a few possible inexact opposites, depending on context. Satisfy, excite, surprise are all valid antonyms (none of them uncommon, so I fail to properly answer the GQ in this instance)