planperioden is the masculine singular definite of planperiode.

planperiodeN

Kven

plaanaperioodiN; plaana-aikaN

Norwegian Bokmål – Kvendict-nob-fkv/src/N_nobfkv.xml:84208Edit on GitHub Suggest

plánaáigodatN

Norsk-nordsamisk ordbokdict-nob-sme/src/N_nobsme.xml:163075Edit on GitHub Suggest

Case	Sg	Pl
Indef	planperiode	planperioder
Def	planperioden	planperiodene