Regarding, respecting.

That which one is concerned in; one's business.

Causing concern; worrying. / (obsolete) Important.

present participle of concern

plural of concerning

(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.

That which affects one’s welfare or happiness. A matter of interest to someone. / The placement of interest or worry on a subject.

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

simple past tense and past participle of concern

Showing concern. / Involved or responsible.