In naval terms:
* Warship: This is the most general synonym, but doesn't capture the specific size or type of frigate.
* Escort: This is a more specific term that captures the traditional role of frigates as protective vessels.
* Destroyer: While technically different, destroyers are similar in size and function to frigates, especially modern ones.
In other contexts:
* Bird: This is a completely different meaning of "frigate" referring to a type of bird. There's no specific synonym for this, but you could use "sea bird" or "water bird" depending on the context.
It's important to consider the context when looking for a synonym for "frigate" to ensure you choose the most appropriate word.