fasten

UK: /ˈfɑːs^ən/ US: /ˈfæsən/ ,(fas′ən, fä′sən)

WordReference Random House Learner's Dictionary of American English © 2025

fas•ten /ˈfæsən/   v. 

1. to attach firmly or securely in place or to something else;
   connect:
   [~ + object] to fasten a light switch securely to the wall.
2. to (cause to) be secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc.: [~ + object]
   Fasten the window.
   [no object]
   This clasp won't fasten.
3. to direct (the eyes, thoughts, etc.) intently;
   focus attention: [~ + object]
   She fastened her eyes on him during the entire performance.
   [~ + on]
   His gaze fastened on the jewels.

fas•ten•er, n. [countable]

WordReference Random House Unabridged Dictionary of American English © 2025

fas•ten  (fas′ən, fä′sən), v.t. 

1. to attach firmly or securely in place;
   fix securely to something else.
2. to make secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc.
3. to enclose securely, as a person or an animal (usually fol. by in):
   to fasten a monkey in a cage.
4. to attach, associate, or connect:
   to fasten a nickname on someone.
5. to direct (the eyes, thoughts, etc.) intently:
   to fasten one's eyes on a speaker.

v.i. 

6. to become fast, fixed, or firm.
7. to close firmly or securely;
   lock:
   This clasp won't fasten.
8. to take a firm hold;
   seize (usually fol. by on or upon):
   to fasten on an idea.
9. to focus attention;
   concentrate (usually fol. by on or upon):
   His gaze fastened on the jewels.

• bef. 900; Middle English fastenen, Old English fæstnian; cognate with Old Norse fastna to betroth; akin to fast¹

Synonyms

• 1. connect, link, hook, clasp, clinch, rivet, clamp, bind, tie, tether.

Collins Concise English Dictionary © HarperCollins Publishers::

fasten / ˈfɑːs^ən/ verb

1. to make or become fast or secure
2. to make or become attached or joined
3. to close or become closed by fixing firmly in place, locking, etc
4. (tr; followed by in or up) to enclose or imprison
5. (transitive) usually followed by on: to cause (blame, a nickname, etc) to be attached (to); place (on) or impute (to)
6. usually followed by on or upon: to direct or be directed in a concentrated way; fix
7. (intransitive) usually followed by on: take firm hold (of)

Etymology: Old English fæstnian; related to Old Norse fastna to pledge, Old High German fastinōn to make fast; see fast¹

ˈfastener noun