Synonyms for Fasten:

n.

grab, hang on, cradle, carry, hold tight, keep hold of something, hold on, assemble, clip. keep, tie up. move. give, impute, blame, place, pin on, assign. fasten (noun)
secure, tighten, fix.

v.

attach (verb)
bond, attach, juxtapose, relate, couple, stick, marry, cling, wed, merge, adhere, affix, bind, abut, hitch, join, annex, splice, connect.
close (verb)
bolt, latch, shut, block, secure, lock, barricade, seal, jam, stop, close.
contact (verb)
fix, secure.
fasten (verb)
grapple, buckle, fuse, lash, zip, clinch, tie, tether, baste, braid, knot, string, bracket, cement, tack, stitch, strap, chain, sew, paste, weld, knit, weave, plait, suture, link, hinge, glue, stay, lace.
make secure; join together (verb)
affix, bond, catch, solder, tighten, close, lace, button, belt, nail, string, moor, chain, couple, bar, cement, jam, tie, infix, fix, attach, rivet, lock, strengthen, lodge, glue, grip, stick, anchor, bolt, hitch, embed, link, wedge, connect, knot, weld, adhere, seal, hold, hook, bind.

Other synonyms:

infix, clasp, unbutton, pin on, close off. impute, block off, unzip, moor, nail, embed, zip up, clip, ingrain, pin. close up, entrench, blame. do up, hook. anchor, lodge. assign, button. bar. belt. catch. attach
tack.
attach to
cling.
cinch
tie down.
clasp
hold fast.
close
shut, shutter.
join
splice.
mend
solder.
nail
rivet.
tie
tie.

Usage examples for fasten

  1. This effort to prove that Lincoln was not a Christian will be condemned by many as an attempt to fasten a stain upon this great man's character. – Abraham Lincoln: Was He A Christian? by John B. Remsburg
  2. Anne was trying to fasten a little gold chain about her throat. – Anne Of The Island by Lucy Maud Montgomery
  3. I don't mean for you to dress my hair and to fasten my gown and all that. – Castle Craneycrow by George Barr McCutcheon