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.

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.

Source: Webster's Revised Unabridged Dictionary (1913)