frigate (n.) Look up frigate at Dictionary.com
1580s, from Middle French frégate (1520s), from Italian fregata (Neapolitan fregate), like many ship names, of unknown origin. Originally a small, swift vessel; the word was applied to progressively larger types over the years, but since 1943 it is used mainly of escort ships.
[A] light nimble vessel built for speed; employed in particular for the gleaning of intelligence and the protection and assault of trade-routes. In battle the frigates took station on the disengaged side of the fleet, where they repeated signals, sped on messages, and succoured the distressed. [Sir Geoffrey Callender, "Sea Passages," 1943]