1. An action, conduct, or manner of acting that occurs infrequently or is uncommon
The bird's rare behavior of flying backwards was fascinating to the ornithologists.
O comportamento raro da ave de voar para trás fascinou os ornitologistas.
2. Unusual or atypical conduct that deviates from normal patterns
His rare behavior of apologizing without being asked surprised everyone.
O seu comportamento raro de se desculpar sem ser solicitado surpreendeu a todos.