viruset is the neuter singular definite of virus.

virusN

Kven

viirysN; viirusN

Norwegian Bokmål – Kvendict-nob-fkv/src/N_nobfkv.xml:74896Edit on GitHub Suggest

virusN

Norsk-nordsamisk ordbokdict-nob-sme/src/N_nobsme.xml:113383Edit on GitHub Suggest

Case	Sg	Pl
Indef	virus	viruser / virus
Def	viruset	virusene / virusa