1. a girl who gives head..alot
2. some one who is known for always deep throating.
"Damn those girls are fuckin troaters! They'll suck anyone up!"
A troater is a slang word for a girl who gives head a lot. Troat can also be used as a verb or adjective.
Gola: Your little sister is such a troater...
Jack: I got some awesome troat last night when Jill came over.
Sarah: That girl is kind of troatey...
Lillian: Yeah you're spot on, she's a total troater.