Denim and Trouser

Denim noun - (usually plural) close-fitting trousers of heavy denim for manual work or casual wear.

Trouser and denim are semantically related. In some cases you can use "Trouser" instead a noun "Denim".

Trouser noun - (usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately.

Denim and trouser are semantically related. Sometimes you can replace term "Denim" with "Trouser", this nouns are similar.