If you mope, you feel miserable and do not feel interested in doing anything. Get on with life and don't sit back and mope. to feel sorry for yourself, without making any effort to do anything or be more happy (Probably from mop, mope (14-16 centuries))
If you mope around or mope about a place, you wander around there not doing anything, looking and feeling unhappy. He moped around the office for a while, feeling bored He mopes about all day