Where does “ro-” come from?

ro- (Middle Irish) comes from Old Irish ro-, from Proto-Celtic ɸro-, from Proto-Indo-European per-, from Proto-Indo-European pr̥tós — passed , crossed.

Ancestry of “ro-”, step by step

StepLanguageWordMeaning
1Old Irishro-indicates a perfective aspect; indicates...
2Proto-Celticɸro-before, in front of; in addition; to completion
3Proto-Indo-Europeanper-before, in front; first; to go through
4Proto-Indo-Europeanpr̥tóspassed , crossed

Words derived from “ro-”

Every word from Proto-Indo-European pr̥tós →Every word from Proto-Indo-European per- →Every word from Old Irish ro- →
ro- — Etymology, Origin & Word History | Etymology Explorer