word-forming element meaning "forward, forth, toward the front" (as in proclaim, proceed); "beforehand, in advance" (prohibit, provide); "taking care of" (procure); "in place of, on behalf of" (proconsul, pronoun); from Latin pro (adv., prep.) "on behalf of, in place of, before, for, in exchange for, just as," which also was used as a first element in compounds and had a collateral form por-.
Also in some cases from cognate Greek pro "before, in front of, sooner," which also was used in Greek as a prefix (as in problem). Both the Latin and Greek words are from PIE *pro- (source also of Sanskrit pra- "before, forward, forth;" Gothic faura "before," Old English fore "before, for, on account of," fram "forward, from;" Old Irish roar "enough"), extended form of root *per- (1) "forward," hence "in front of, before, toward, near," etc.
The common modern sense of "in favor of, favoring" (pro-independence, pro-fluoridation, pro-Soviet, etc.) was not in classical Latin and is attested in English from early 19c.
word-forming element denoting "kinship one degree further removed," early 15c. (in great uncle), from great (adj.), based on similar use of French grand (see grand-). An Old English way of saying "great-grandfather" was þridda fæder, literally "third father;" in early Middle English furþur ealdefader was used (12c.).
before vowels, hol-, word-forming element meaning "whole, entire, complete," from Greek holos "whole, entire, complete," also "safe and sound;" as a noun, "the universe," as an adverb, "on the whole;" from PIE *sol-wo-, from root *sol- "whole." Often translated as whole, which it resembles but with which it apparently has no etymological connection.
word-forming element meaning "pressure," from Greek piezein "to press tight, squeeze," from PIE *pisedyo- "to sit upon" (source also of Sanskrit pidayati "presses, oppresses"), from *pi "on," short for *epi (see epi-) + root *sed- (1) "to sit." First in piezometer (1820), an instrument for ascertaining or testing pressure. It was in common use in word formation from c. 1900.
word-forming element meaning "outside; beyond the scope of; in addition to what is usual or expected," in classical Latin recorded only in extraordinarius, but more used in Medieval Latin and modern formations; it represents Latin extra (adv.) "on the outside, without, except," the old fem. ablative singular of exterus "outward, outside," comparative of ex "out of" (see ex-).
word-forming element in words of Latin origin, "apart, away," from Latin se-, collateral form of sed- "without, apart, aside," probably originally "by one's self, on one's own," and related to sed, Latin reflexive pronoun (accusative and ablative), from PIE *sed-, extended form of root *s(w)e-, pronoun of the third person and reflexive (source also of German sich; see idiom).
word-forming element meaning "below, beneath," from Latin infra (adverb and preposition) "below, underneath, on the under side, beneath," also "later than; smaller than; inferior to," related to infernus "low, below," from PIE *ndher "under" (source also of Sanskrit adnah "below," Old English under "under, among;" see under). Modern popular use of it dates from the 1920s, as an opposite to super-, often in science fiction. "This use of infra- is scarcely a Latin one" [OED].
word-forming element meaning "around, round about, all around, on all sides," from Latin adverb and preposition circum "around, round about," literally "in a circle," probably accusative form of circus "ring" (see circus). The Latin word was commonly used in word-formation. In French, the element became circon-; Kitchin points out that con for cum is common even in classical Latin. For sense development, compare German rings "around."
word-forming element meaning "above, over, beyond," from Latin super (adverb and preposition) "above, over, on the top (of), beyond, besides, in addition to," from *(s)uper-, variant form of PIE root *uper "over." In English words from Old French, it appears as sur-. The primary sense seems to have shifted over time from usually meaning "beyond" to usually meaning "very much," which can be contradictory. E.g. supersexual, which is attested from 1895 as "transcending sexuality," from 1968 as "very sexual."