'Tightening' definitions:

Definition of 'tightening'

From: WordNet
noun
The act of making something tighter; "the tightening of economic controls" [ant: laxation, loosening]

Definition of 'Tightening'

From: GCIDE
  • Tighten \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. [1913 Webster]
  • Just where I please, with tightened rein I'll urge thee round the dusty plain. --Fawkes. [1913 Webster]
  • Tightening pulley (Mach.), a pulley which rests, or is forced, against a driving belt to tighten it. [1913 Webster]