ymrwymo (Welsh) comes from Welsh ym-, from Proto-Indo-European h₂m̥bʰi, from Proto-Indo-European h₂n̥tbʰi, from Proto-Indo-European h₂énts, from Proto-Indo-European h₂ent-, from Proto-Indo-European h₂en- — on, onto.
ymrwymo (Welsh): to commit oneself, to oblige oneself