gadfly
/ˈgædflaɪ/noun
(pl. -flies)
1- a fly that bites livestock, especially a horsefly, warble fly, or botfly虻, 牛虻（尤指马蝇、皮瘤蝇等）。
1.1
- figurative an annoying person, especially one who provokes others into action by criticism〈喻〉讨人厌者（尤指批评他人而促其行动的人）。
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