The term for words that have definitions that are opposite of one another is ‘contronym’. Here are 15 good examples of words that are a ‘contronym’:

1. Dust

Dust the shelves (removing particles)
Dust the crops (applying particles)

2. Fast

Move fast (go quickly)
Holding fast (fixed or unmoving)

3. Help

Help (to assist)
Can’t help doing something (prevent)

Singapore usage: to ask someone to do something, rather than to assist

4. Hold

I hold up my end of the bargain (to support)
If there is a hold up (to hinder)

5. Left

The gentlemen have left (departed)
and the ladies are left. (remaining)

6. Off

If a light goes off, (deactivated).
If an alarm goes off, (activated)

7. Out

If the lights are out (invisible)
If the stars are out (visible)

8. Oversight

If I have oversight (I am responsible)
If I make an oversight (I fail to be responsible)

9. Peer

In a jury of one’s peers (a person of equal status)
The members of the peerage (higher status)

10. Sanction

Give official permission for an action (approval)
Impose a penalty on (boycotting)

11. Screen

To screen something (a movie) (to show)
If something screens you (an unsightly view) (to hide)

12. Seed

If you seed a field (add seeds)
If you seed grapes (remove seeds)

13. Stone

You can stone some rambutans (remove)
Don’t stone your neighbour (add)

(Even if he likes to get stoned. Singapore meaning of Stoned)

14. Trim

If you’re trimming the tree are you using tinsel or a chain saw?
If I trim the tree (put stuff on it)
If I trim the grass, (I cut stuff off of it)

15. Weather

If I weather the storm (endures)
If the wind weathers the mountain (erodes)