Second string and Second-rater

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.

Second-rater and second string are semantically related In some cases you can use "Second-rater" instead a noun phrase "Second string".

Second-rater noun - A person of second-rate ability or value.

Second string and second-rater are semantically related in sidekick topic. You can use "Second string" instead a noun phrase "Second-rater".