B1
very unusual
Dictionary examples:
It's rare to find a phone that makes coffee, but mine does! (0.0)
My rare talent is falling up stairs instead of down. (0.0)
My plant has a rare ability: it waters itself when thirsty. (0.0)
It's very rare to see these birds in winter. (23.5)
a rare occasion/opportunity (30.9)
a rare disease/species (34.6)