They are mīs and tīs; so far as I can tell, they are found exclusively in Old Latin inscriptions (i.e. you won’t encounter them in archaic imitations of Old Latin designed by Classical authors). The more you know…
If anyone has further thoughts or resources on these, feel free to share below.
The words enim, etenim and neque enim are all postpositive tools for emphasis. They typically occur in the second position, but may occur in the third, where the second word is emphatic.
Enim and its emphatic counterpart, etenim, may add an affirmative pulse to a statement or clause. In this sense, they function much as equidem, certē and vērō, though these are not necessarily postpositive.
…sed enim istaec captio est: …but this is clearly a trick!
in hīs est enim aliqua obscūritās: in fact, these matters contain some mystery.
Quid agis?—Nihil enim: What are you up to?—Nothing, truly! (~Nothing, I swear!)
Etenim is very popular in parenthetical phrases.
dux huius agminis Caesar est (etenim est prīmus mīlitum): the leader of this line is Caesar, because, of course, he is the first among soldiers.
Kate Medoppidum (quae etenim modo hērēdem peperit) nōn trēs diēs vīsaest: Kate Middleton, who as you know just gave birth to the heir, has not been seen for three days.
The comparatives plūs, minus, amplius, and longius may be seen operating without the use of quam while performing the same semantic work. Generally, these operate with a measure or number and no change in case.
Plūs septigentī captī sunt. More than seven hundred were taken.
Plūs teriī parte interfectā, nos perditī esse putāvimus, With more than one-third slain, we thought ourselves done for.
Aditus in lātitūdinem nōn amplius ducentōrum pedum relinquēbātur. An approach of not more than two hundred feet in width was left. (Genitive of measure.)
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