Second-string and Sub

Second-string adjective - Being a replacement or substitute for a regular member of a team.

Sub and second-string are semantically related. in lesser topic. In some cases you can use "Sub" instead an adjective phrase "Second-string".

Sub noun - A large sandwich on a long split roll.

Second-string and sub are semantically related. Sometimes you can use "Second-string" instead an adjective "Sub".