Enter a clue or pattern or both:
The Clue
Obsolescent directories (10 letter answer)
The Answer
PHONEBOOKS
Tags
Notes
The answer PHONEBOOKS is so rare that it appears less than once every 2500 puzzles.
Definition
PHONEBOOK as a noun:
1. (phonebook, phone book, telephone book, telephone directory) = a directory containing an alphabetical list of telephone subscribers and their telephone numbers