pact (n.) Look up pact at Dictionary.com
early 15c., from Old French pacte "agreement, treaty, compact" (14c.), from Latin pactum "agreement, contract, covenant," noun use of neuter past participle of pacisci "to covenant, to agree, make a treaty," from PIE root *peg- "to coagulate, become fixed" (source also of 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").