Definition of "impactor" [impactor]

• Any of several machines or devices in which a part impacts on another, or on a material (noun)

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• "Frankly, I think a major impactor is probably the most likely. abb1 says:"
• "The impactor is expected to make a spectacular, football field-sized crater, seven to 15 stories deep, in the speeding comet."
• "Keith's note: Hmm, LCROSS is an "impactor" - something that will crash into the moon at high speed."