Proto-Indo-European root forming prepositions, etc., meaning "forward," and, by extension, "in front of, before, first, chief, toward, near, against," etc.
It forms all or part of: afford; approach; appropriate; approve; approximate; barbican; before; deprive; expropriate; far; first; for; for-; fore; fore-; forefather; foremost; former (adj.); forth; frame; frau; fret; Freya; fro; froward; from; furnish; furniture; further; galore; hysteron-proteron; impervious; improbity; impromptu; improve; palfrey; par (prep.); para- (1) "alongside, beyond; altered; contrary; irregular, abnormal;" paradise; pardon; paramount; paramour; parvenu; pellucid; per; per-; percent; percussion; perennial; perestroika; perfect; perfidy; perform; perfume; perfunctory; perhaps; peri-; perish; perjury; permanent; permeate; permit; pernicious; perpendicular; perpetual; perplex; persecute; persevere; perspective; perspire; persuasion; pertain; peruse; pervade; pervert; pierce; portray; postprandial; prae-; Prakrit; pre-; premier; presbyter; Presbyterian; preterite; pride; priest; primal; primary; primate; primavera; prime; primeval; primitive; primo; primogenitor; primogeniture; primordial; primus; prince; principal; principle; prior; pristine; private; privilege; privy; pro (n.2) "a consideration or argument in favor;" pro-; probably; probe; probity; problem; proceed; proclaim; prodigal; produce; profane; profess; profile; profit; profound; profuse; project; promise; prompt; prone; proof; proper; property; propinquity; prophet; prose; prostate; prosthesis; protagonist; Protean; protect; protein; Proterozoic; protest; proto-; protocol; proton; protoplasm; Protozoa; proud; prove; proverb; provide; provoke; prow; prowess; proximate; Purana; purchase; purdah; reciprocal; rapprochement; reproach; reprove; veneer.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pari "around, about, through," parah "farther, remote, ulterior," pura "formerly, before," pra- "before, forward, forth;" Avestan pairi- "around," paro "before;" Hittite para "outside of," Greek peri "around, about, near, beyond," pera "across, beyond," paros "before," para "from beside, beyond," pro "before;" Latin pro "before, for, on behalf of, instead of," porro "forward," prae "before," per "through;" Old Church Slavonic pra-dedu "great-grandfather;" Russian pere- "through;" Lithuanian per "through;" Old Irish ire "farther," roar "enough;" Gothic faura "before," Old English fore (prep.) "before, in front of," (adv.) "before, previously," fram "forward, from," feor "to a great distance, long ago;" German vor "before, in front of;" Old Irish air- Gothic fair-, German ver-, Old English fer-, intensive prefixes.
"earlier; preceding, as in order of time," 1714, from Latin prior "former, previous, first;" figuratively "superior, better;" as a noun "forefather; superior rank;" comparative of Old Latin pri "before" (from PIE *prai-, *prei-, from root *per- (1) "forward," hence "in front of, before, first"). Also used adverbially (with to), by 1706.
"an ancestor, a forefather," 1650s, from Medieval Latin primogenitor, from Latin primo (adv.) "first in order of time; at first," from primus "first" (see prime (adj.)) + genitor "father," from genitus, past participle of gignere "to beget" (from PIE root *gene- "give birth, beget"). Related: Primogenital; primogenitary. The fem. form is primogenitrix (1875). The rights of a second son are secundogeniture.
late 14c., predecessour, "one who has held an office or position before the present holder," from Old French predecesseor "forebear" and directly from Late Latin praedecessorem (nominative praedecessor) "one who has gone before," from Latin prae "before" (see pre-) + decessor "retiring official," from decess-, past participle stem of decedere "go away," also "die" (see decease (n.)). Meaning "ancestor, forefather" is recorded from c. 1400.
1833, in biology, "reversion by influence of heredity to ancestral characteristics, resemblance of a given organism to some remote ancestor, return to an early or original type," from French atavisme, attested by 1820s, said to have been coined by French botanist Antoine-Nicolas Duchesne, from Latin atavus "ancestor, forefather," from at- perhaps here meaning "beyond" + avus "grandfather," from PIE *awo- "adult male relative other than the father" (see uncle).