Steel drum and Timpani

Steel drum noun - A concave percussion instrument made from the metal top of an oil drum; has an array of flattened areas that produce different tones when struck (of Caribbean origin).

Timpani and steel drum are semantically related. in percussion instrument topic. In some cases you can use "Timpani" instead a noun phrase "Steel drum".

Timpani noun - A large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it.

Steel drum and timpani are semantically related. Sometimes you can replace phrase "Steel drum" with "Timpani", this terms are similar.