Iontrálacha san Fhoclóir Nua Béarla-Gaeilge a bhrabhsáil
- old-world
- olde
- olden
- older
- oldest
- oldie
- oldish
- ole
- oleander
- oleic acid
- olfactory
- oligarch
- oligarchic
- oligarchy
- oligopoly
- olive
- olive branch
- olive oil
- olivine
- ombudsman
- omega
- omega-3
- omelette
- omen
- ominous
- ominously
- omission
- omit
- omnibus
- omnipotence
- omnipotent
- omnipresence
- omnipresent
- omniscience
- omniscient
- omnivore
- omnivorous
- on
- on behalf of
- on-air
- on-board
- on-call
- on-duty
- on-field
- on-road
- on-screen
- on-site
- on-street
- on-target
- on-the-job