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.
hibernation - estivation
intrepid - trepid
kosher - tref
Firefox is telling me all three of those opposites are misspelled. Shows what it knows.
Defenestration, while not a common word, does have an opposite, fenestration, but I’ve only seen it used in a medical context. It means to cut a hole in someone.
As in trepidation?
If the opposite of first is ultimate, then you can say the opposite of second is penultimate and the opposite of third is antepenultimate.
Somewhat the inverse, but the negative disgruntled is far more common than the positive gruntled.
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)
Apparently “disappoint” once meant “to fail to keep an appointment” and its meaning morphed from there. It’s still true that if you don’t show up for an appointment with me, you’ve disappointed me. 
Indeed (that’s why I specified modern English). I expect there will be quite a few of these, not limited to negation prefixes either.
I’ve always seen it spelled trayf. Dictonary.com says both are acceptable.