1. to behave in a manner that is not proper, dignified, or socially acceptable; to conduct oneself inappropriately or impolitely
He acted indecorously at the formal dinner by speaking loudly and interrupting others.
Ele agiu de forma indecorosa no jantar formal ao falar alto e interromper os outros.
2. to engage in unseemly or ungraceful conduct; to behave with lack of decorum
The guests who acted indecorously were asked to leave the reception.
Os convidados que agiram indecoradamente foram solicitados a deixar a recepção.