a rope, chain, or the like, by which an animal is fastened to a fixed object so as to limit its range of movement.

the utmost length to which one can go in action; the utmost extent or limit of ability or resources.

to fasten or confine with or as if with a tether. ?

at the end of one's tether, at the end of one's resources, patience

or strength.

verb

unchain , unfasten , unshackle

noun

binding , bond , chain , cord , fetter , halter , harness , lead , leash , picket , restraint , rope , shackle

verb

batten , bind , chain , fetter , leash , manacle , moor , picket , restrain , rope , secure , shackle , tie , band , cable , fasten , limit , scope