名詞 ratter:

1. a disloyal person who betrays or deserts his cause or religion or political party or friend etc.
   同義詞：deserter, apostate, renegade, turncoat, recreant
2. any of several breeds of terrier developed to catch rats
   同義詞：rat terrier

rat.ter

n.（名詞）
One that catches or kills rats:
捕鼠者：捕捉或獵殺老鼠的人或動物：
例句：
Many terriers are good ratters.
很多狗是很好的捕鼠動物

Slang One who betrays or deserts another.
【俚語】 出賣他人者，拋棄他人者