Tether

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.
Digital Technology. to use (an electronic device, usually a smartphone or tablet) to enable a wireless Internet connection on another nearby device, often a laptop:
There’s no wi-fi, so I’ll have to tether my phone to my laptop.
Digital Technology. to use an electronic device to enable a wireless Internet connection on another device.
at the end of one’s tether, at the end of one’s resources, patience, or strength.
Contemporary Examples

We would lack a human face as our symbol; we would exist in the ether of ideas with no concrete stake in the ground to tether us.
128 Years Old and Still a Looker: Happy Birthday to Lady Liberty Elizabeth Mitchell October 27, 2014

Power for the sensors flows up the tether and data flows down.
Why Old-School Airships Now Rule Our Warzones Bill Sweetman June 29, 2014

In this conversation, Rick realizes that to survive, he must tether himself to the present—to these people.
The Walking Dead’s Luke Skywalker: Rick Grimes Is the Perfect Modern-Day Mythical Hero Regina Lizik October 27, 2014

Even the always-energetic Atti looked like he was at the end of his tether.
My Attack of Model Jealousy Anonymous February 8, 2014

Historical Examples

I showed him the tether on my foot, and the stake that dragged after it.
The Memoirs of a White Elephant Judith Gautier

If you’ll unpack the mare and tether her, Haggis, we can see aboot the fire and the meat.
The Fiery Totem Argyll Saxby

But we could find no other stable, and were therefore obliged to tether the unhappy animals to the filthy mangers.
The Bible in Spain George Borrow

When he was pretty nearly at the end of his tether he came back to England.
Doctor Luttrell’s First Patient Rosa Nouchette Carey

I camped a little before sundown at a small open place to tether the horses.
Explorations in Australia, The Journals of John McDouall Stuart John McDouall Stuart

They are also beyond the tether of my subject, which I fear I have already overstrained.
The Journal of Negro History, Volume 6, 1921 Various

noun
a restricting rope, chain, etc, by which an animal is tied to a particular spot
the range of one’s endurance, etc
at the end of one’s tether, distressed or exasperated to the limit of one’s endurance
verb
(transitive) to tie or limit with or as if with a tether
n.

late 14c., “rope for fastening an animal,” probably from Old Norse tjoðr “tether,” from Proto-Germanic *teudran (cf. Danish tøir, Swedish tjuder, Old Frisian tiader, Middle Dutch tuder, Dutch tuier “line, rope,” Old High German zeotar “pole of a cart”), from PIE root *deu- “to fasten” + instrumentive suffix *-tro-. Figurative sense of “measure of one’s limitations” is attested from 1570s.
v.

late 15c., from tether (n.). Related: Tethered; tethering.
see: end of one’s rope (tether)