A shit that doesn't want to come out and really hurts.

The horror and shame of getting old; especially when approaching the age of gray hair and arthritis.

is the Nacho that all the cheese is attached too. Every plate of Nachos has one.

the central part of an atom.
Contains protons and neutrons.

(n. v. adj. pronoun, adverb, etc.) - word used as an alternative to a word one cannot think of due to a temporary lapse in brain function or laziness.

(interjection) - used as an exclamation of pain, surprise, pity, complaint, dislike, joy, etc.

(noun) - used to inadvertently acknowledge the presence of a good looking woman