backscatter

noun

1. (countable, uncountable)The deflection of particles or radiation through angles greater than 90 degrees to the original direction of travel.
2. (countable, uncountable)The particles or radiation deflected in this manner.
3. (countable, uncountable)A portion of the energy of electromagnetic radiation such as a laser or radio waves that is scattered back in the direction of the source of radiation by an obscurant.
4. (countable, uncountable)The sending of IP packets to essentially random addresses in response to incoming packets that have a spoofed origin.

verb

1. (ambitransitive)To scatter particles or radiation back to the direction from which they originate.