Real Dictionary

diminish
verb: If you diminish someone or something, you talk about them or treat them in a way that makes them appear less important than they really are.
verb: When something diminishes, or when something diminishes it, it becomes reduced in size, importance, or intensity.

diminish in American English
to become smaller or less
to make, or make seem, smaller; reduce in size, degree, importance, etc.; lessen
intransitive verb: to lessen; decrease
transitive verb: to make or cause to seem smaller, less, less important, etc.; lessen; reduce