What part of speech is スティール製?

Question

What part of speech is スティール製{せい} from スティール製{せい}カテノイドexpression?
I know スティール is a noun (steel), 製{せい} is a suffix (made of), but I don't know their value together. スティール製{せい} is a noun or an adjective?

Answer 1

スティール製 works as "a noun that can be treated as a so-called no-adjective". A native Japanese speaker who only knows 学校文法 would probably say it's a noun phrase as a whole.

Whether it's a noun or an adjective depends on how you define adjectives, which is not easy.

• Why does Japanese have two kinds of adjectives? (-i adjectives and -na adjectives)
• What is the definition of adjective in japanese?

Answer 2

スティール製 (along with all other words using the 製 suffix) is what's sometimes referred to as a の-adjective; essentially a grammatical noun with an adjectival meaning.

の-adjectives can modify other nouns in the same ways that any noun can - which is to say, by using the の particle (eg. 木製のテーブル "a wooden table") or, as in your スティール製カテノイド example, by combining directly to form a compound noun. The の method is more productive and can be used to describe anything, while noun compounds are usually only used for a more limited number of established expressions.