Tight·en v. t. [imp. & p. p. Tightened p. pr. & vb. n. Tightening.] To draw tighter; to straiten; to make more close in any manner.
Just where I please, with tightened rein
I'll urge thee round the dusty plain. --Fawkes.
Tightening pulley Mach., a pulley which rests, or is forced, against a driving belt to tighten it.
n : the act of making something tighter; "the tightening of
economic controls" [ant: loosening]