verb
1.
to cause one thing to hold to another
fasten a feather to a hat
Synonyms: affix, attach, fix, rivet
Related Word: connect, join, link, unite; adhere, cleave, cling, cohere, stick
Contrasted words: divide, divorce, part, separate, sever, sunder; loose, loosen
Antonyms: unfasten
2.
to fix in place or in a desired position
fasten the door
Synonyms: anchor, catch, fix, moor, secure
Related Word: bed, implant, infix, lodge, set, settle; embed, join, wedge; establish; bar, hitch, hook
Idioms: make fast ( or secure or sure)
Contrasted words: loose, undo, unloose, unloosen
Antonyms: unfasten
3.
to direct (as attention or hope) directly and steadily
fastened his whole mind on the problem
Synonyms: concenter, concentrate, fix, fixate, focus, put, rivet
Related Word: address, apply, devote, direct, train, turn
Contrasted words: falter, vacillate, waver