It forms all or part of: caret; cashier (v.) "dismiss;" cassation; caste; castellan; castellated; Castile; castle; castigate; castrate; castration; chaste; chastity; chateau; chatelaine; Chester; forecastle; incest; quash (v.) "make void, annul."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit sastra- "knife, dagger;" Greek keazein "to split;" Latin carere "to be cut off from," cassus "empty, void;" Old Church Slavonic kosa "scythe."
1580s, from French frégate (1520s), from Italian fregata (Neapolitan fregate), which with many names for types of sea vessels is of unknown origin. It is common to the Mediterranean languages (Spanish, Portuguese, Catalan fragata). Originally a small, swift vessel; the word was applied to progressively larger types over the years.
[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]
In the old sailing navy usually they carried guns on a raised quarter-deck and forecastle, hence frigate-built (1650s) of a vessel having the quarter-deck and forecastle raised above the main-deck.
also man-handle, mid-15c., "wield a tool," also, late 15c., "to attack (an enemy)," from man (n.) + handle (v.). Nautical meaning "to move by force of men" (without levers or tackle) is attested from 1834, and is the source of the slang meaning "to handle roughly" (1865). Related: Manhandled; manhandling.
[T]he two Canalers rushed into the uproar, and sought to drag their man out of it toward the forecastle. Others of the sailors joined with them in this attempt, and a twisted turmoil ensued; while standing out of harm's way, the valiant captain danced up and down with a whale-pike, calling upon his officers to manhandle that atrocious scoundrel, and smoke him along to the quarter-deck. [Melville, "The Town-Ho's Story," Harper's magazine, October 1851]