Definition of mule-killer in English:

mule-killer

noun

US
  • Any of several arthropods supposed to kill livestock by stinging them, as a whip scorpion, dragonfly, or praying mantis.

Origin

Mid 19th century (in an earlier sense). From mule + killer.

Pronunciation

mule-killer

/ˈmjuːlˌkɪlə/