By the Bitter End Meaning?

: until the end of something that may be very bad, unpleasant, etc. I knew she would stand by me to the bitter end.

What means to the bitter end?

to the bitter end until the finish of a task, job, or undertaking, however unpleasant or difficult. until final defeat or death.

Where does the term the bitter end come from?

Bitter goes back to the early seventeenth century. It appears first in Captain John Smith's Seaman's Grammar of 1627. It meant the end of a cable or rope that remained fixed on board ship when it was being paid out through the bitts. The word would seem to be bitt plus -er, as in header, rounder and cropper.