propagate (v.)

"an agreement between persons or parties," early 15c., from Old French pacte "agreement, treaty, compact" (14c.) and directly from Latin pactum "agreement, contract, covenant," noun use of neuter past participle of pacisci "to covenant, to agree, make a treaty," from PIE root *pag- "to fasten." Related: Paction "act of making a pact."

also *pak-, Proto-Indo-European root meaning "to fasten."

It forms all or part of: Areopagus; appease; appeasement; compact (adj.) "concentrated;" compact (n.1) "agreement;" fang; impact; impale; impinge; newfangled; pace (prep.) "with the leave of;" pacific; pacify; pact; pagan; page (n.1) "sheet of paper;" pageant; pale (n.) "limit, boundary, restriction;" palette; palisade; patio; pawl; pax; pay; peace; peasant; pectin; peel (n.2) "shovel-shaped instrument;" pole (n.1) "stake;" propagate; propagation; travail; travel.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pasa- "cord, rope," pajra- "solid, firm;" Avestan pas- "to fetter;" Greek pegnynai "to fix, make firm, fast or solid," pagos "pinnacle, cliff, rocky hill;" Latin pangere "to fix, to fasten," pagina "column," pagus "district;" Slavonic paž "wooden partition;" Old English fegan "to join," fon "to catch seize."

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.