Other forms: tightened, tightening, tightens
To tighten something is to make it firmer, closer or less loose. A screw given another quarter turn, a belt pulled to the next hole, a jar lid you cannot open because someone tightened it too hard.
It stretches well past nuts and bolts. Governments tighten rules, banks tighten lending, an airport tightens security, and all of them mean less slack than before. Tighten up is the everyday phrasal version, used of defences, deadlines and sloppy writing. Bodies tighten too: her throat tightened, his grip tightened on the wheel. The opposite is loosen, and when money runs short a family tightens its belt.
1verbtightenTo make something firmer or less loose, or to become firmer.
“Tighten the bolts before you sit on that chair.”
2verbruleTo make a rule, control or system stricter.
“The council voted to tighten the rules on parking.”
3verbbodyOf a part of the body: to become tense.
“His jaw tightened when she said the name.”
Tighten looks like tight with -en stuck on the end, and that is how English treats it now. The history is stranger: it comes from Middle English tighten, from Old English tyhtan, and started out with no connection to tight, which was Old English thiht. The two words drifted together until they looked like family.
Old English
tyhtan
Middle English
tighten
English, today
tighten
Synchronically equivalent to tight + en, but actually derived from Middle English tighten, from Old English tyhtan, thus originally unrelated to tight (Old English þiht).
Etymology from Wiktionary, CC BY-SA