You would think, given the vast tribe of verbal compounds with inter- as a prefix, that a few species of intrā-compounds would also inhabit that wood of the Latin dictionary. In fact, they are highly endangered, perhaps even extinct. Here are a few compound adjectives and nouns that I discovered; the verbs were nowhere to be found.
Here are some irregular adverbs that defy the rules set up in this post.
diū, diūtius, diūtissimē, for a long time, for a longer time, for the longest time
potius, ——potissimum, rather, first of all
saepe, saepius,saepissimē, often, more often/again, most often
satis, satius, —— enough, preferable
secus, sētius, —— otherwise, worse
multum (or multō), magis (or mage), maximē, much, more, most
parum, minus, minimē, not enough, less, least
nūper, ——, nūperrimē, newly, most newly
temperē, temperius, —— seasonably, more seasonably
Most of these are either disconnected from their corresponding adjectives (semantically), or are defective in either comparative or superlative form. However, the real outlier here is the multum/ō, magis/e, maximē set, which is an aggregate of various options. Multō is of course the ablative singular neuter for the positive adjective, and mage the neuter accusative of the comparative adjective.
Magis and maximē may also be paired with other adjectives to create their comparatives, especially in adjectives ending in -eus or -ius (in the positive.)
idōneus, magis idōneus, maximē idōneus, fit, more fit, most fit
The adjectival suffixes -ārius, -tōrius, and -sōrius denote belonging to a group qualified by the implied content of the correspond root. Effectively, these adjectives are formed by the addition to -ius to theadjectival root -āris or the nominal root -or. Let’s build a few examples.
A few things to notice about this pattern: (i) the original base of the adjective can be just about anything—noun, adjective, verb, adverb—but the penultimate word is always a noun or an adjective. That said, (ii) the penultimate noun or adjective is not always extant in Latin; note the [brackets]. Finally, note that (iii) this set of adjectives is often theoretical—rēs bellatōriae (matters of warriors)and rēs extrāriae (matters of foreigners) probably cover half the total appearances of those two adjectives.