participant (adj.)

"sharing, having a share or part," late 15c., from Old French participant and directly from Latin participantem (nominative participans), present participle of participare "to share in, partake of," from particeps "sharing, partaking" (see participation).

"one who participates, a partaker," 1560s, from Middle French participant, from Latin participantem (nominative participans), present participle of participare "to share in, partake of" from particeps "sharing, partaking" (see participation).