(transitive) To relate or belong to; to have reference to or connection with; to affect the interest of; to be of importance to. / (transitive) To engage by feeling or sentiment; to interest.

(Internet slang) Used to express concern on the part of the speaker in response to something.

Showing concern. / Involved or responsible.

simple past tense and past participle of concern

(obsolete) concerned; having involvement or responsibility

(obsolete, rare) Relevance.

feeling of worry or anxiety

(obsolete) The state or quality of being a concern / That in which one is concerned or interested; concern; affair; interest. / importance; moment; consequence / concern; participation; interposition

Causing concern; worrying. / (obsolete) Important.

Regarding, respecting.