Meaning: out of options or alternatives (definition).


Example: My cell phone was locked in the car with my keys and wallet - I was at the end of my rope.
Origins: A rope thrown to someone for help or provided as a resource. (Sources. OED [b])


Rewrites: at the loose end of an untethered rope (rescue) grabbed the short end of a shrinking rope (resource) ran out of ladder reduced to pennies and pocket lint bailing with a bottomless pail at the mercy of a slippery rope with no grip on the last strand of an unraveling rope watched the rescue party pass me by
Discussion: Different from “at the end of my tether” (see OED [a] above for distinction. Also sometimes thought to mean “I can’t take anymore.” I didn't address those here.