impact is on the Academic Word List.

Pronunciation

change

Singular
impact

Plural
impacts

Impact is on the Academic Vocabulary List.
  1. (countable) An impact is the act of one object hitting another.
    In tests, the driver was unhurt, even in high-speed impacts.
    Many buildings were destroyed as the plane exploded on impact.
  2. (countable & uncountable) The impact is the effect of an act, statement, change, etc.
    The report noted that most teachers feel that IT has made little impact on formal education.
    The environmental impact of such increases in efficiency, however, depends on how you generate the power.

Plain form
impact

Third-person singular
impacts

Past tense
impacted

Past participle
impacted

Present participle
impacting

  1. If something impacts you, it has an effect on you.
    It is obvious how bad movies will impact on children.
  2. If you impact something, you press (or pack) its together.
    There is a special tool to impact the road when it is under construction so the base is solid.