A bitter taste is unpleasant. It’s acrid and sharp, and the sharpness is the key to why it’s called “bitter.” That’s because “bitter” used to be the Old English word “biter,” a word that was just what it sounds like; something that bites. A bitter taste “bites” your tongue, so to speak.
Having begun with a taste of something bitter you might decide to persevere down to the bitter end and eat the whole thing regardless. If you do, though, you’d be eating something that bites your tongue, but to a different end than you might guess. The “bitter end” means following through until something is finished no matter the consequences. But it doesn’t have anything to do with the “bitter” that’s a taste. At least it probably doesn’t.
A “bitt” is a nautical term for posts on a ship (or a dock) that you secure ropes with. There are usually two of them (or one device with two “horns”) so you can “figure-8” your rope around them quickly to fasten it without complicated knots. Speed isn’t always important when you’re tying your ship to the dock, but when your rope is controlling a sail I’m told it can be critical (I know nothing about sailboats).
One thing about most ropes is that they have ends. On a ship, one of those ends is used for fastening to the bitts. And as Admiral William Smyth put it 1867: “When a chain or rope is paid out to the bitter-end, no more remains to be let go.” So that’s where the expression comes from, right?
Well…maybe, but on the other hand maybe not. After all, just “paying your rope out to the bitter end” doesn’t suggest anything unpleasant, which common usage of “the bitter end” does seem to imply. In fact, “the bitter end” used to be frequently employed to describe a situation in which somebody died. You could imagine a dire outcome from coming to the end of your rope (I mean, besides just noticing another common expression popping up), but your ship would have to be in a fairly unusual situation to encounter something like that. Common phrases more often come from common events than rare ones.
“Bitter end” shows up in some other contexts though, and enough centuries ago to suggest that maybe the nautical association wasn’t its original meaning. Or possibly there were two different “bitter end” phrases from two different sources. In any case, the 1611 King James Bible included this: “For the lips of a strange woman drop as an honeycomb, and her mouth is smoother than oil: But her end is bitter as wormwood…”
In 1622, another religious book included similar verses:
“With hunger parch’d, and consumed with heat,
I will enforce them to a bitter end;
The teeth of beasts I will upon them set,
And will the pois’nous dust-fed serpent send.”
It’s not really clear where the “bitter end” originated there, but that bit about the dire outcome is pretty plain. It shows up again in this poem from 1744:
“Tho’, by her own curs’d arts the woman fell,
With care, unbounded, did I not attend,
And, undeserving, sooth’d her bitter end,
Clasp’d her cold limbs, beheld the dead’ning eye,
And, thro’ my lips, receiv’d her [last] sigh.”
It’s possible that “bitter end” started as a nautical term and acquired its connotation from the association with unpleasant taste. But if you follow the trail down to the bitter end, you’ll find that there’s yet another kind of “bitter.” In the 1400s a “bit” was a fire bucket (used in a bucket brigade), and a “bitter” was a fireman who used one. And there can be a pretty dire outcome from a fire, so maybe…