Second string and Sub

Second string noun - A squad of players that are available either individually or as a team to relieve or replace the players who started the game.

Sub and second string are semantically related. In some cases you can use "Sub" instead the phrase "Second string" as a noun or an adjective.

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

Second string and sub are semantically related. Sometimes you can use "Second string" instead a noun "Sub".