■ verb
1》 close or do up securely.
↘fix or hold in place.
↘( ~ something off ) secure the end of a thread with stitches or a knot.
2》 ( ~ on/upon ) single out (something) and concentrate firmly on it.
Derivatives
~er noun
Origin
OE fæstnian 'make sure, confirm', also 'immobilize', of W. Gmc origin; related to fast 1 .