1. A form, shape, or variant that deviates from what is typical, standard, or expected
The disease presented in an atypical form that was difficult to diagnose.
A doença apresentou uma forma atípica que foi difícil de diagnosticar.
2. In medical or scientific contexts, an unusual or non-standard manifestation of a condition
The patient experienced an atypical form of the infection with mild symptoms.
O paciente apresentou uma forma atípica da infecção com sintomas leves.