S: (n) untying, undoing, unfastening (loosening the ties that fasten something) "the tying of bow ties is an art; the untying is easy"
S: (n) tightening (the act of making something tighter) "the tightening of economic controls"
S: (n) take-up (the action of taking up as by tightening or absorption or reeling in)
S: (n) accommodation ((physiology) the automatic adjustment in focal length of the natural lens of the eye)
S: (n) adaptation ((physiology) the responsive adjustment of a sense organ (as the eye) to varying conditions (as of light))
S: (n) dark adaptation (the process of adjusting the eyes to low levels of illumination; cones adapt first; rods continue to adapt for up to four hours)
S: (n) light adaptation (the process of adjusting the eyes to relatively high levels of illumination; the pupil constricts and the cones system is operative)
S: (n) tune (the adjustment of a radio receiver or other circuit to a required frequency)
S: (n) change, alteration, modification (an event that occurs when something passes from one state or phase to another) "the change was intended to increase sales"; "this storm is certainly a change for the worse"; "the neighborhood had undergone few modifications since his last visit years ago"