There are a very small number of irregular comparative and superlative of adverbs
[i] multum: a lot > magis: more > maximē:
the most; mostly; chiefly / especially
ī ad illum quem magis amās quam patrem (Seneca the
Elder) │ Go to him whom you love more than the father.
Cato’s recommendation to take
time when buying a farm, and not just to visit it once: Quotiēns ībis, totiēns magis
placēbit quod bonum erit. │ However often you (will) go, each time what will be
good will please you more.
quam ob rem mihi magis pār
est viā dēcēdere et concēdere (Plautus) │ For this reason, it is more
fitting to get out of the road and to make room for me.
exoptā id quod vīs maximē
tibi ēvenīre: fīet (Plautus) │ Long for what you desire the most to
happen to you; it shall be done.
Ubi ego erō? / Ubi maximē
esse vīs (Plautus) │ Where shall I be? / Where you most want to be.
Uxōrēs habent dēnī* duodēnīque*
inter sē commūnēs et maximē frātrēs cum frātribus parentēsque cum līberīs
(Caesar)│ Ten and even twelve have wives common to them, and particularly
brothers among brothers, and parents among their children.
*dēnus, -a, -um: ten (each); duodēnus, -a, -um: twelve
(each)
[ii] parum: not enough > minus: less > minimē:
least (of all); very little; no; not at all
Pacidēius suōs equitēs exporrigere coepit in longitūdinem,
quī nihilō minus ¦ fortissimē ācerrimēque
pugnābant. (Dē bellō Āfricō; adapted) │ Pacideius began to deploy his horsemen
on a broader front, and they still fought with the utmost gallantry and spirit.
[= and no less did they fight most bravely and (most)
fiercely]
Quid vīs, Pamphile? / Pa. Hinc abīre mātrem? minimē.
(Terence) │ What do you want, Pamphilus? / PAMPHILUS: My mother go away? By
no means.
Iam illud minimē mīrum est (Cicero) │ Now that is not
at all strange
Nicostrātus quīdam, fidēlis Oppianicī servolus, percūriōsus
et minimē mendāx (Cicero) │ a certain Nicostratus, a faithful slave of
Oppianicus's, a man who was very curious and by no means a liar
[iii] diū: for a long time > diūtius: for longer;
for too long > diūtissimē: for the longest time; for a very
long time
Nam mihi quidem quotīdiē augēscit magis / Dē fīliō
aegritūdō; et quantō diūtius / abest, magis cupiō tantō et magis
dēsīderō. (Terence)│ For really my sorrow about my son increases [= grows more]
daily; and the longer he is away from me, so much more do I wish
for him, and the more I miss him.
Superlative adverb and adjective in the same sentence:
Quī diūtissimē impūberēs permānsērunt, maximam
inter suōs ferunt laudem. (Caesar) │ Those who have remained virgins for the
longest time, they bear the greatest praise amongst their own
people.
[iv] potius: rather > potissimum: first
of all; above all; in preference to all; most preferably
Quidquid est, ipse ībit potius (Plautus) │ Whatever
it is, he’ll rather go there himself.
vōbīs nārrābō potius meās nunc miseriās (Plautus) │ I
will rather [ = I’ll prefer to] relate my woes to you.
[v] saepe: often > saepius: more often > saepissimē: most
often
Quīn melius nōvī quam tū et vīdī saepius. (Plautus)
│ Why, I know him better than yourself, and have seen him more times.
tū mē dē tuīs rēbus omnibus et dē Lentulī tuī nostrīque studiīs et exercitātiōnibus velim quam familiārissimē certiōrem et quam saepissimē faciās (Cicero) │ I should like you to write about all your affairs, and about the studies and training of your son Lentulus (whom I regard as mine also) as confidentially and as frequently as possible