OK, I didn’t want to make the title too long here, so it was stated in a way that would get more attention. This is the question:
There is an adjective which has a similar form using the exact same word preceded by the Latin prefix in-, with the following function:
a prefix of Latin origin, corresponding to English un-, having a negative or privative force, freely used as an English formative, especially of adjectives and their derivatives and of nouns (inattention; indefensible; inexpensive; inorganic; invariable ).
Yet, both the adjective and its in+adjective variation basically mean the same thing. That is, despite the negating in-, they aren’t antonyms. Note that I didn’t say exactly the same thing, but basically the same. An example: if attention and inattention meant basically the same thing. They obviously don’t, so that’s not the pair.
Hint: the adjective comes from Latin. I know that’s not a very big hint, but there it is. 🙂
And the explanation for why we can have this apparent little morphological paradox is obviously found in the Latin roots, the respective etymology of the words in question.
Easy to think of?