1. third person singular present indicative of 'ser' (to be) + adjective 'impensado' (thoughtless, unthinking, rash, unpremeditated)
It is thoughtless to speak without considering the consequences.
É impensado falar sem considerar as consequências.
2. describes an action or behavior that is done without thought or consideration
His decision was rash and unthinking.
A decisão dele é impensada e precipitada.