'Pom-pom' definitions:

Definition of 'pom-pom'

(from WordNet)
noun
Decoration consisting of a ball of tufted wool or silk; usually worn on a hat [syn: pompon, pom-pom]
noun
Artillery designed to shoot upward at airplanes [syn: antiaircraft, antiaircraft gun, flak, flack, pom- pom, ack-ack, ack-ack gun]

Definition of 'Pom-pom'

From: GCIDE
  • Pompom \Pom"pom`\, Pom-pom \Pom"-pom`\, n. [Imitative.] (Mil.) originally, a Vickers-Maxim one-pounder automatic machine cannon using metallic ammunition fed from a lopped belt attached to the gun; -- popularly so called from its peculiar drumming sound in action. More recently, the term is applied mostly to automatic antiaircraft cannons. [Webster 1913 Suppl. +PJC]