all seasons; year-round
Used as a noun to refer to something that spans or is suitable for all seasons.
This resort can be enjoyed in all seasons.
noun which may take the genitive case particle 'no'
all-season; suitable for any season
Used as a prenominal modifier (with の) to describe items or facilities usable throughout the year.
I bought all-season tires.
Variant with a middle dot; less common but seen in some contexts.
Loanword from English 'all season(s)'.