WordWeb Online

1. With regard or relation to; on the subject of
   "I have a query concerning your previous reply";
   - regarding, about, respecting, re, apropos, as regards, with regard to, as for, as to, in connection with

1. Causing distress, worry or anxiety
   "concerning news";
   - distressing, distressful, disturbing, perturbing, troubling, worrisome, worrying

1. Be relevant to
   - refer, pertain, relate, come to, bear on, touch, touch on, have to do with
    
2. Be on the mind of
   - interest, occupy, worry

See also: heavy

Encyclopedia: Concern