diagnosen is the masculine singular definite of diagnose.

diagnoseN

Kven

diagnoosiN

Norwegian Bokmål – Kvendict-nob-fkv/src/N_nobfkv.xml:107161Edit on GitHub Suggest

diagnosaN

Norsk-nordsamisk ordbokdict-nob-sme/src/N_nobsme.xml:215032Edit on GitHub Suggest

Case	Sg	Pl
Indef	diagnose	diagnoser
Def	diagnosen	diagnosene