1 deep, (far) downwards or inwards, way down, deep down:
The glacier was deeply fissured. She swam to the surface and inhaled deeply.
2 profoundly, intensely, strongly, powerfully, very much, acutely, keenly, gravely, greatly, to a great extent, extremely, thoroughly, completely, entirely, seriously, severely, irrevocably, unreservedly; passionately, heavily, emotionally:
She is deeply involved with a man from Kent. They were deeply committed to the labour movement.