Noel or Noël /nō-elˈ/

1. Christmas (also Nowel or Nowell; obsolete except in Christmas carols, on Christmas cards, etc)
2. (without cap) a Christmas carol

• 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