1. A sound wave, of the same amplitude but of opposite phase to that of an unwanted sound, that can cancel the unwanted sound using destructive interference

Encyclopedia: Antinoise

• purple finch
• purple fringeless orchid
• purple fringeless orchis
• purple gallinule
• purple grackle
• purple granadillo
• purple ground cherry
• purple heart
• purple heather
• purple loco
• purple locoweed
• purple loosestrife
• purple martin
• purple milk vetch
• purple mullein
• purple nightshade
• purple onion
• purple orchis
• purple osier
• purple passage
• purple patch
• purple pea
• purple poppy mallow
• purple rock brake
• purple sage