a. From adjectives of the first and second declensions by changing the characteristic vowel of the stem to -é: as, cáré, dearly, from cárus, dear (stem cáro-); amícé, like a friend, from amícus, friendly (stem amíco-).
NOTE: The ending -é is a relic of an old ablative in -éd (cf. § 43. N. 1).
b. From adjectives of the third declension by adding -ter to the stem. Stems in nt- (nom. -ns) lose the t-. All others are treated as i-stems: -
NOTE: This suffix is perhaps the same as -ter in the Greek -
c. Some adjectives of the first and second
declensions have adverbs of both forms (-é and -ter). Thus dúrus, hard, has both dúré and dúriter; miser, wretched, has
both miseré and miseriter.
d. The neuter accusative of
adjectives and pronouns is often used as an adverb: as, multum, much; facile, easily; quid, why.
This is the origin of the ending -ius in the comparative degree of adverbs
(§ 218): as, ácrius,
more keenly (positive ácriter); facilius, more easily (positive facile).
NOTE: These adverbs are strictly cognate accusatives
(§ 390).
e. The ablative singular neuter or
(less commonly) feminine of adjectives, pronouns, and nouns may be
used adverbially: as, falsó,
falsely; cito, quickly
(with shortened o); réctá (viá), straight
(straightway); crébró, frequently;
volgó, commonly;
forte, by chance; sponte, of one's own accord.
NOTE: Some adverbs are derived from adjectives not in use:
as, abundé, plentifully
(as if from abundus; cf. abundó, abound); saepe, often (as if from saepis, dense, close-packed; cf. saepés, hedge, and saepió, hedge in).