D defs.my
Entry 1 sense Webster, 1913

Tighten

/tīt'-ən/ · Tight·en · IPA /ˈtaɪ.tən/
01 v. t. To draw tighter; to straiten; to make more close in any manner.
imp. & p. p. Tightened; p. pr. & vb. n. Tightening
  1. 1.
    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.
Phrases & compounds
Tightening pulley — a pulley which rests, or is forced, against a driving belt to tighten it.