1. (major) effect or result (of something)
'Impact' is a word that can be used as a verb - 'to impact' - meaning to affect someone or something strongly or dramatically: "The impact of this decision will be felt throughout the company." "The emotional impact of losing her brother was enormous." It can be used as a noun to describe hitting something at force, such as 'an impact in a car accident' or 'the window smashed on impact with the ball." This word can be used in any context.