1. removing tacks or small nails from something
2. changing direction while sailing by turning the bow through the wind
Usage: nautical

Examples

• She was untacking the poster from the bulletin board.
• The carpenter spent time untacking the old trim.
• After untacking the fabric, she could reposition it properly.
• The sailor was untacking to avoid the rocks ahead.
• They were untacking the boat to catch the favorable wind.
• Untacking the notice took only a few seconds.