You're about to stumble into the looking-glass world of contronyms.
  1. Sanction
    Can mean ‘give official permission or approval for (an action)’ or conversely, ‘impose a penalty on.’
  2. Left
    Can mean either remaining or departed. (The gentlemen have left and the ladies are left.)
  3. Seed
    If you seed the lawn you add seeds, but if you seed a tomato you remove them.
  4. Off
    Means ‘deactivated,’ as in "to turn off," but also ‘activated,’ as in "The alarm went off."
  5. Weather
    Can mean ‘to withstand or come safely through,’ as in “The company weathered the recession,” or it can mean ‘to be worn away’: “The rock was weathered.”
  6. Clip
    Can mean 'to bind together' or 'to separate.' You clip sheets of paper to together or separate part of a page by clipping something out.
  7. Go
    Means 'to proceed,' but also 'give out or fail.'
  8. Bitch
    Can derisively refer to a woman who is considered overly aggressive, or it can refer to someone passive or submissive.
  9. Out (of)
    Means 'outside' or 'inside': “I hardly get out of the house because I work out of my home.”
  10. Screen
    Can mean ‘to show’ (a movie) or ‘to hide’ (an unsightly view).
  11. Fine
    Can mean excellent (a fine wine) or barely acceptable (“OK. That’s fine. Whatever”).
  12. Reservations
    Either a firm commitment or a hesitation about something. “Will you be dining with us tonight?” “Yes, we have reservations.” Or is it, “No, we have reservations”?
  13. Wind up
    When you wind something up are you preparing it to start or stop? That depends on whether it’s an old fashioned clock or a long-winded speech.
  14. Oversight
    Oversight is the noun form of two verbs with contrary meanings, 'oversee' and 'overlook.' 'Oversee' means ‘supervise.’ 'Overlook' usually means the opposite: ‘to fail to see or observe; to pass over without noticing; to disregard, ignore.’
  15. Cleave
    Can mean 'to cling to or adhere,' or 'to split or sever (something).'
  16. Resign
    This one only works in writing. 'Resign,' meaning 'to quit,' is spelled the same as 'resign,' meaning 'to sign up again.'