Technically, I suppose, it's a noun serving as an adjective, but it's an adjective nonetheless. In English, we do not pluralize adjectives. We sign multiyear contracts not multi-years contracts . And there's more. The adjectives in your sample sentence are richer than many adjectives.
Compound modifiers are two or more words that join together to form a single concept.
When compound modifiers are placed before a noun, they are hyphenated to eliminate the possibility of ambiguity. In your sample sentence, there are three compound modifiers that are placed before nouns. All must be hyphenated. Return to Online Writing Lab home page.