As a noun (meaning a repeated phrase in a song or poem):
* Adlais: This is the most common translation, directly meaning "refrain" or "chorus."
* Coriws: This literally translates to "chorus," and can also be used as a synonym for "refrain."
As a verb (meaning to abstain from something):
* Ymroi: This means "to refrain" or "to abstain."
* Gwrthod: This means "to refuse" or "to decline," and can also be used to express refraining from something.
* Ymatal: This means "to abstain" or "to withhold."
Therefore, the best translation for "refrain" depends on the specific context of your sentence. For example:
* "The refrain of the song is catchy." -> "Adlais y gân yw un sy'n dal i'r gân."
* "I refrained from eating dessert." -> "Ymroi i mi rhag bwyta pwdin."
It's always a good idea to consider the context and use the most appropriate translation for your specific situation.