Without knowing anything more (like what room it is in, when the house was built), I'd advise doing this. Plug a turned on lamp with a good incandescent bulb into that outlet. Have someone watch the bulb like a hawk to notice if it blinks on even for a split second while you do the following. Go around to all outlets in the area, including nearby rooms, and plug something else into these, one after another, wiggling that item side-to-side a bit in each receptacle. You could also pound on the wall or ceiling by switches and lights. If your partner at any time yells that they saw any light from that bulb, you are at the place that needs a connection improved. Turn off power to investigate and repair there.
