Second fiddle and Second-class

Second fiddle noun - A secondary role or function.

Second-class and second fiddle are semantically related. In some cases you can use "Second-class" instead an adjective phrase "Second fiddle".

Second-class adjective - Of little or less value or merit.

Second fiddle and second-class are semantically related. Sometimes you can replace phrase "Second fiddle" with "Second-class", this phrases are similar.