Thayer's Greek Lexicon

 1. full of labours, annoyances, hardships
  1) pressed and harassed by labours
  2) bringing toils, annoyances, perils; of a time full of
peril to Christian faith and steadfastness; causing pain and
trouble
2. bad, of a bad nature or condition
  1) in a physical sense: diseased or blind
  2) in an ethical sense: evil wicked, bad

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The word is used in the nominative case in Mt. 6:13. This usually
denotes a title in the Greek. Hence Christ is saying, deliver us
from "The Evil", and is probably referring to Satan.