Enter a clue or pattern or both:
The Clue
Obsolescence, in a way (11 letter answer)
The Answer
USELESSNESS
Tags
Notes
The answer USELESSNESS is so rare that it appears less than once every 2500 puzzles.
Definition
USELESSNESS as a noun:
1. (inutility, uselessness, unusefulness) = the quality of having no practical use