—n.
1 a rope etc. by which an animal is tied to confine it to the spot.
2 the extent of one's knowledge, authority, etc.; scope, limit.
—v.tr. tie (an animal) with a tether.
Phrases and idioms:
at the end of one's tether having reached the limit of one's patience, resources, abilities, etc.
Etymology: ME f. ON tjoacutethr f. Gmc
Useful english dictionary. 2012.