8.3.1. Adverbs are regularly formed from Nouns, Pronouns and Adjectives as follows:
A. From Pronouns:
I. With a nasal lengthening, added systematically to zero-grade forms, which gives adverbs in -am; as, tam, qam, peram (from lat.)
II. An -s lengthening, added to the adverb and not to the basic form, giving sometimes alternating adverbs; as, ab/abs, ek/eks, ambhi/ambhis, etc.
III. An -r lengthening; as, qor, qir, etc. which is added also to other derived adverbs. It is less usual than the other two.
Some older adverbs, derived as the above, have specialized as suffixes for adverb derivation, forming compound adverbs from two pronoun stems:
i. From the pronoun de, the nasalized dem gives adverbs in -dem, -dam; as, idem, qidam, etc.
ii. From root dhe there are two adverbs which give suffixes with local meaning, from stems of pronouns, nouns, adverbs and prepositions:
a. an adverb in -m, dhem/dhm; as, endhem, prosdhm, etc.
b. an adverb in -i, dhi, as in podhi, autodhi, etc.
iii. From the root te there are also some adverbial suffixes with mood sense (also temporal, derived from it). So ti; as, iti or itidem, ut(i), proti, auti, etc; and t-(e)m, utm, item, eitm, etc.
B. From nouns and adjectives (usually neuter accusatives), frozen as adverbs already in IE III. The older endings to form Adverbs are the same as those above, i.e. -i, -u and -(e)m, which are thus original Adverbs, and not only secondary forms. These Adverbs have normally precise, local meaning, not only abstract or deictic, and derive then usually in temporal meanings. The endings -i, -u, -r, as well as nasal -n and also -s, as in the pronoun formations, are also given.
NOTE 1. It is not uncommon to find adverbs derived from noun stems which never had inflection, thus (probably) early frozen as adverbs in its pure stem.
NOTE 2. From these adverbs derived conjunctions with temporal-consecutive meaning (then, so) or contrastive (on the contrary, instead).
Some examples of known adverbs are:
ambhi, mbhi, on both sides, around
ana, on, over, above;
anti, opposite, in front
apo, po, out, from
au/wo, out, far
en(i) / n, in
epi, opi, pi: towards here, around, circa
et(i), oti; beyond, past; over, on the other side;
per, pr: in front, opposite, around
qu, from interrogative-indefinites qi/qo
upo, under, down; uper(i), up.