Impact, collision, shock, concussion mean a forceful, even violent contact between two or more things. Impact may be used to imply contact between two things, at least one of which is impelled toward the. See examples of impact used in a sentence.
The noun impact can refer to a physical force (like a collision), an influence (a bad role model or a hero), or a strong effect (a foot of snow will have an impact on driving conditions). The impact that something has on a situation, process, or person is a sudden and powerful effect that it has on them. Definition of impact noun in oxford advanced learner's dictionary.