tail end

1. The hindmost part.
2. The very end; the conclusion.

noun

The hindmost part of something: end, rear¹, tag end, tail. See precede/follow.

1.  The rear or hindmost part, as in Douglas was at the tail end of the academic procession. [Mid-1700s]
2.  The very end, the conclusion, as in Only at the tail end of his speech did he thank his sponsors. [Mid-1800s]

The noun has 3 meanings:

Meaning #1: the time of the last part of something
  Synonyms: fag end, tail

Meaning #2: any projection that resembles the tail of an animal
  Synonym: tail

Meaning #3: the fleshy part of the human body that you sit on
  Synonyms: buttocks, nates, arse, butt, backside, bum, buns, can, fundament, hindquarters, hind end, keister, posterior, prat, rear, rear end, rump, stern, seat, tail, tooshie, tush, bottom, behind, derriere, fanny, ass