acorn

noun4

1. •
   The fruit of the oak, being an oval nut growing in a woody cup or cupule.
2. •
   [usually plural] (slang) A testicle.
3. •
   (informal) The glans penis.

   • The Romans, likewise, represented the uncouth Priapus—the god of rustic fertility and sexual assault—as comically well endowed, with his acorn showing. — 2021
4. •
   A cone-shaped piece of wood on the point of the spindle above the vane, on the mast-head.