• his strength is slowly waning
• our supply of ammunition steadily wanes
• descending, regressive, waning
• attenuate, to abate, to attenuate, to ax, to axe, to bate, to curtail, to cut back, to cut down, to cut, cut, to deflate, to depress, to derogate, to detract, to diminish, to draw in, to ease, to ease down, to gear down, to lessen, to lower, to narrow, to pare down, to pull in, to put down, to reduce, to release, to send down, to sink, sank, sunk, to slack, to slacken, to step down, to subdue, to taper, to temper, to tone down