1. In a disloyal and faithless manner
   "he behaved treacherously"
   - faithlessly, traitorously, treasonably, false

See also: treacherous

• Megaloptera
• megalosaur
• Megalosauridae
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• megaparsec
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• Megapodius
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• Megaptera novaeangliae
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• megatherian mammal
• megatheriid
• Megatheriidae
• Megatherium
• megaton
• megaton bomb