Fixed expressions
Idioms
English fixed expressions — phrases whose meaning isn't obvious from the individual words. Each entry shows the meaning, an example sentence, and its register.
Idioms containing once, including its inflections. Clear word filter
3 idioms
once in a blue moon
CEFR B1Very rarely, almost never.
Neutral
once in a while
CEFR B1occasionally, but not often
Neutral
once and for all
CEFR B2finally and permanently, so the matter will not need to be handled again
Neutral