renvoi or (esp formerly) renvoy /ren-voiˈ, French rã-vwäˈ/

1. Sending back by a government of an alien to his or her own country
2. A referring or relegation of a legal dispute to another jurisdiction

• once in a blue moon
• once in a way
• once in a while
• once more
• once or twice
• once-over
• once-overs
• oncer
• oncers
• onces
• once upon a time
• onchocerciases
• onchocerciasis
• oncidium
• oncidiums
• on cloud nine
• onco-
• oncogen
• oncogene
• oncogenes
• oncogeneses
• oncogenesis
• oncogeneticist
• oncogeneticists
• oncogenic