noun
Kōjien (Japanese dictionary published by Iwanami Shoten)
A well-known comprehensive Japanese dictionary first published in 1955; often used as a reference for word meanings and usage.
広辞苑で言葉の意味を調べた。
I looked up the meaning of the word in Kōjien.
The title 広辞苑 (Kōjien) is a proper noun for a specific dictionary; it is not a general word with a derivational etymology.