fasten

fasten /ˈfæsn̩/ Brit /ˈfɑːsn̩/ verb
fastens; fastened; fastening
fasten
/ˈfæsn̩/ Brit /ˈfɑːsn̩/
verb
fastens; fastened; fastening
Britannica Dictionary definition of FASTEN
1 
a  [+ object] : to attach (something) or join (two things or two parts of something) especially by using a pin, nail, etc.
b  [no object] of parts of something : to become attached or joined
2 
a  [+ object] : to put something in a position or location in such a way that it will not move
b  : to close and lock (something, such as a window or door)
[+ object]
[no object]
3 
: to grip and hold something with (your hand, teeth, etc.)
[+ object]
[no object]

fasten on

[phrasal verb]
fasten (something) on (something) or fasten on (something)
: to direct (something, such as your eyes or attention) to (something)

fasten onto

[phrasal verb]
fasten onto (something)
: to grip and tightly hold (something)
— often used figuratively

— fastener

/ˈfæsn̩ɚ/ Brit /ˈfɑsn̩ɚ/ noun, plural fasteners [count]