Reserves and Second-string

Reserves noun - Civilians trained as soldiers but not part of the regular army.

Second-string and reserves are semantically related In some cases you can replace phrase "Second-string" with "Reserves", this terms are similar.

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

Reserves and second-string are semantically related in group of substitute players topic. Sometimes you can use "Reserves" instead a noun phrase "Second-string".