Antagonyms

The following words can mean both one thing and its opposite. For each word, use both meanings in a sentence.

• Buckle: to hold together (e.g. buckle your belt) vs. to fall apart (e.g., buckle under pressure)
• Clip: to attach vs. to cut off
• Cut: get in (as in line or queue) vs. get out (as in a school class)
• Dust: To remove dust vs. To apply dust (as in fingerprinting)
• Effectively: in effect (doing the equivalent of the action but not the real thing) vs. with effect (doing the action and doing it well) [Contrast "he is effectively lying" (colloquial?) with "he is lying effectively"]
• Fix: to restore to function (fixing the refrigerator) vs. to make non-functional (fixing the dog)
• Mad: carried away by enthusiasm or desire vs. carried away by hatred or anger
• Rocky: Firm, steadfast vs. tending to sway (e.g., a rocky shelf)
• Scan: to examine closely vs. to look over hastily
• Transparent: Easily seen ("His motives were transparent.") invisible

Richard Lederer coined the term contranyms for them. Independently Charles Ellis came up with antagonyms (where this list came from). They're also known as auto-antonyms and Janus words.