1. at a time that is not suitable, convenient, or favorable for something to happen
He arrived at an inopportune moment when she was in an important meeting.
Ele chegou num momento inoportuno quando ela estava em uma reunião importante.
2. at a badly timed or inconvenient time
The power outage occurred at an inopportune moment during the live broadcast.
A queda de energia ocorreu num momento inoportuno durante a transmissão ao vivo.