WordNet sense 1 (so lacking in interest as to cause mental weariness):

dull, ho-hum, irksome, slow, tedious, tiresome, wearisome, deadening

WordNet sense 2 (arousing no interest or attention or curiosity or excitement):

uninteresting

WordNet sense 3 (the act of drilling):

drilling

WordNet sense 4 (the act of drilling a hole in the earth in the hope of producing petroleum):

oil production