-bu Godan/u-verb

1. to grow wild; to run to waste; to become degenerate
2. to become rough (of art, craft, etc.); to lose refinement; to deteriorate (of skill)
3. to intensify (of wind, rain, etc.); to become more severe (usu. after -masu stem)
4. archaic to do as one pleases; to amuse oneself; to play around