1. An unannounced or unplanned visit to someone, made without prior arrangement or notice
My mother made an impromptu visit to my apartment yesterday without calling first.
Minha mãe fez uma visita de improviso ao meu apartamento ontem sem avisar antes.
2. A spontaneous call or drop-in at a location without scheduled appointment
The impromptu visit from the health inspector caught the restaurant off guard.
A visita de improviso do inspetor de saúde pegou o restaurante desprevenido.