214. Adverbs are regularly formed from adjectives as follows.
a. From adjectives of the 1st and 2nd declensions by changing the characteristic vowel of the stem to -ē.
cārē  dearly [from cārus  dear (cāro-)] 
amīcē  like a friend [from
        amīcus  friendly (amīco-)]
      
Note— The ending -ē is a relic of an old ablative in -ēd (cf. § 43, Note 1).
b. From adjectives of the 3rd declension by adding -ter to the stem. Stems in nt- (nom. -nst-). All others are treated as i-stems.
fortiter  bravely [from fortis (stem forti-)  brave]
        
ācriter  eagerly [from ācer (stem ācri-)  eager]
vigilanter  watchfully [from vigilāns (stem
        vigilant-)] 
prūdenter  prudently [from prūdēns (stem prūdent-)]
aliter  otherwise [from
        alius (old stem ali-)]
Note— This suffix is perhaps the same as -ter in the Greek -τερος and in uter, alter. If so, these adverbs are in origin either neuter accusatives (cf. d.) or masculine nominatives.
c. Some adjectives of the 1st and 2nd declensions have adverbs of both forms (-ē and -ter). Thus dūrus (hard) has both dūrē and dūriter; miser (wretched) has both miserē and miseriter.
d. The neuter accusative of adjectives and pronouns is often used as an adverb.
multum  much 
facilĕ  easily 
quid  why
This is the origin of the ending -ius in the comparative degree of adverbs (§ 218).
ācrius  more keenly (positive ācriter) 
facilius  more easily (positive
        facilĕ)
Note— These adverbs are strictly cognate accusatives (§ 390).
e. The neuter ablative singular or (less commonly) feminine of adjectives, pronouns, and nouns may be used adverbially
falsō  falsely 
citŏ  quickly (with shortened o) 
rēctā (viā)  straight (straightway) 
crēbrē; frequently 
volgō  commonly 
fortĕ  by chance 
spontĕ  of one's own accord
Note— Some adverbs are derived from adjectives not in use.
abundē  plentifully (as if from
          †abundus; cf. abundō abound)
          
saepĕ  often (as if from †saepis  dense, close-packed; cf. saepēs  hedge, and saepiō  hedge in).
215. Further examples of adverbs and other particles which are in origin case forms of nouns or pronouns are given below. In some the case is not obvious, and in some it is doubtful.
1. Neuter Accusative forms.
nōn (for nē-oinom, later ūnum)  not 
iterum (comparative of i- stem of is)  a second time
        
dēmum (superlative of dē down)
         at last
2. Feminine Accusatives.
partim  partly 
statim  on the spot 
saltim  at least (generally saltem), from lost nouns in -tis (genitive -tis)
Thus -tim became a regular adverbial termination; and by this means adverbs were made from many noun and verb stems immediately, without the intervention of any form which could have an accusative in -tim.
sēparātim separately from sēparātus separate
Some adverbs that appear to be Feminine Accusative are possibly instrumental.
palam  openly 
perperam  wrongly 
tam  so 
quam  as
3. Plural Accusatives.
aliās  elsewhere 
forās  out of doors (as end of motion)
So perhaps quia because
4. Ablative or Instrumental forms
quā  where 
intrā  within 
extrā  outside 
quī  how 
aliquī  somehow 
forīs  out of doors 
quō  whither 
adeō  to that degree 
ultrō  beyond 
citrō  this side (as end of motion) 
retrō  back 
illōc (for †illō-ce) weakened to illūc  thither
Those in -trō are from comparative stems (cf. ūls, cis, re-).
5. Locative forms.
ibi  there 
ubi  where 
illī, illī-c  there 
peregrī (peregrē)  abroad 
hīc (for †hī-ce)  here
Also the compounds hodiē (probably for †hōdiē) today; perendiē day after tomorrow.
6. Of uncertain formation.
a. Those in -tus (usually preceded by i), with an ablative meaning.
funditus  from the bottom, utterly 
dīvīnitus  from above, providentially 
intus  within 
penitus  within
b. Those in -dem, -dam, -dō.
quidem  indeed 
quondam  once 
quandō (cf. dōnec)  when
c. Those in dum (probably accusative of time) while; iam now
216. A phrase or short sentence has sometimes grown together into an adverb (cf. notwithstanding, nevertheless, besides).
postmodo  presently (a short time after) 
dēnuō (for dē novō)  anew 
vidēlicet (for vidē licet)  to wit (see, you may) 
nihilōminus  nevertheless (by nothing the less)
Note— Other examples are:
anteā [old antideā]
           before (ante eā, probably ablative or instrumental) 
īlicō (in locō)  on the spot, immediately 
prōrsus  absolutely
            (prō vorsus  straight ahead) 
rūrsus (re-vorsus)  again 
quotannīs  yearly (quot
                annīs  as many years as there are) 
quam-ob-rem  wherefore 
cōminus (con manus)
             hand to hand
ēminus (ex
                manus)  at long range
nīmīrum (nī mīrum)  without doubt 
ob-viam (as in
            īre obviam  to go to meet) 
prīdem (cf. prae and -dem in i-dem)  for some time 
forsan
            (fors an)  perhaps (it's a chance whether)
            
forsitan (fors sit an)  perhaps (it would be a chance whether) 
scīlicet (†scī, licet)  that is to say (know, you may; cf. ī-licet  you may go)
            
āctūtum (āctū  on the
              act, and tum  then)
217. The classes of Adverbs, with examples, are as follows.
a. Adverbs of Place1
| hīc here | hūc hither | hinc hence | hāc by this way | 
| ibi there | eō thither | inde thence | eā by that way | 
| istīc there | istūc thither | istinc thence | istā by that way | 
| illīc there | illūc thither | illinc thence | illā (illāc) by that way | 
| ubi where | quō whither | unde whence | quā by what way | 
| alicubi somewhere | aliquō somewhither | alicunde from somewhere | aliquā by some way | 
| ibīdem in the same place | eōdem to the same place | indidem from the same place | eādem by the same way | 
| alibī elsewhere, in another place | aliō elsewhere, to another place | aliunde from another place | aliā in another way | 
| abiubi wherever | quōquō whithersoever | undecunque whencesoever | quāquā in whatever way | 
| ubivīs anywhere, where you will | quōvīs anywhere, whither you will | undique from every quarter | quāvī by whatever way | 
| sĭcubi if anywhere | sīquō if anywhere, (anywhither) | sīcunde if from anywhere | sīquā if anywhere | 
| nēcubi lest anywhere | nēquō lest anywhither | nēcunde lest from anywhere | nēquā lest anywhere | 
Note— The demonstrative adverbs hīc, ibi, istīc, illīc, and their correlatives, correspond in signification with the pronouns hīc, is, iste, ille (see § 146), and are often equivalent to these pronouns with a preposition
inde = ab eō, etc.
So the relative or interrogative ubi corresponds with quī (quis), ali-cubi with aliquis, ubiubi with quisquis, sī-cubi with sīquis (see § 147 - § 151, with the table of correlatives in § 152).
ūsque  all the way to 
usquam  anywhere 
nusquam  nowhere 
citrō  to this side 
intrō  inwardly 
ultrō  beyond (or freely, i.e. beyond what is required) 
porrō  further on
quōrsum (for quō
              vorsum  whither turned?)  to what end? 
hōrsum  this way 
prōrsum  forward (prōrsus utterly) 
intrōrsum  inwardly 
retrōrsum  backward 
sūrsum  upward 
deorsum  downward 
seorsum  apart 
aliōrsum  another way
b. Adverbs of Time
quandō  when? (interrogative) 
cum (quom)  when (relative) 
ut  when, as 
nunc  now 
tunc (tum)  then 
mox  presently 
iam  already 
dum  while 
iam diū, iam dūdum, iam prīdem  long ago, long since
prīmum (prīmō)  first 
deinde (posteā)  next after 
postrēmum (postrēmō)  finally 
posteāquam, postquam 
        when (after that, as soon as)
umquam (unquam)  ever 
numquam (nunquam)  never 
semper  always
aliquandō  at some time, at length 
quandōque (quandōcumque)  whenever 
dēnique  at last
quotiēns (quotiēs)  how often 
totiēns  so often 
aliquotiēns  a number of times
cotīdiē  every day 
hodiē  today 
herī  yesterday 
crās  tomorrow 
prīdiē  the day before 
postrīdiē  the day after 
in diēs  from day to day
nōndum  not yet 
necdum  nor yet 
vixdum  scarce yet 
quam prīmum  as soon as possible
        
saepe  often 
crēbrō  frequently 
iam nōn  no longer
c. Adverbs of Manner, Degree, or Cause
quam  how, as
        
tam  so 
quamvīs  however much, although 
paene  almost 
magis  more 
valdē  greatly 
vix  hardly
cūr, quārē  why 
ideō, idcircō, proptereā  on this account, because 
eō  therefore 
ergō, itaque, igitur  therefore
ita, sīc  so 
ut (utī)  as, how 
utut, utcumque  however
d. Interrogative Particles
an, -ne, anne, utrum, utrumne, num whether
nōnne, annōn whether not
numquid, ecquid whether at all
On the use of Interrogative Particles, see § 332, § 335.
e. Negative Particles
nōn  not (in simple denial) 
haud, minimē  not (in contradiction) 
nē  not (in prohibition)
nēve, neu  nor 
nēdum  much less
nē  lest 
neque, nec  nor 
nē . . . quidem  not even
nōn modo . . . vērum (sed) etiam not only . . . but also
nōn modo . . . sed nē . . . quidem not only not . . . but not even
sī minus  if not 
quō minus (quōminus)  so as not
quīn (relative) but that (interrogative), why not?
nē, nec (in composition)  not (so in nesciō  I know not)
negō  I say no (âiō  I say yes) 
negōtium  business (†nec-ōtium)
nēmō (nē- and hemō, old form of homō)  no one 
nē quis  lest any one 
neque
            enim  for . . . not
For the use of Negative particles see § 325 ff.
For the Syntax and Peculiar uses of Adverbs, see § 320 ff.
218. The Comparative of adverbs is the comparative form of the corresponding adjective, declined in the neuter accusative; the Superlative is the adverb in -ē formed regularly from the superlative of the adjective.
cārē  dearly
        (cārus  dear) 
cārius 
cārissimē
miserē [miseriter]  wretchedly (from miser  wretched) 
miserius 
miserrimē
leviter (from levis  light) 
levius 
levissimē
audācter [audāciter] (from audāx  bold)
        
audācius 
audācissimē
benĕ  well (from bonus  good) 
melius 
optimē
malĕ  ill (from
        malus  bad) 
pêius 
pessimē
a. The following are irregular or defective.
diū  long (in time) 
diūtius 
diūtissimē
      
potius  rather
        
potissimum  first of all, in preference to all
saepe  often 
saepius  oftener, again
        
saepissimē
satis  enough 
satius  preferable
secus  otherwise 
sētius  worse
multum (multō)  much
magis  more 
maximē  most
parum  not enough 
minus  less 
minimē  least
nūper  newly 
nūperrimē
temperē  seasonably 
temperius
Note— In poetry the comparative mage is sometimes used instead of magis.