The act of achieving something the achievement of an ambition is a result gained by effort accomplishment being honored for her academic achievements a major scientific achievement.

An achievement is a great accomplishment—something achieved with great effort or skill.

Achieve and achievement often imply the completion of something important or difficult—a lofty goal or a great feat. Graduating high school is an achievement. Learning a new language is an achievement. An award is an achievement.

Achievement can also refer to the act of achieving, as in We need to focus on the achievement of these goals. This sense of the word doesn’t always imply impressiveness by itself—it often means the same thing as completion.