quasiparticle

quasiparticle [kwey-zahy-pahr-ti-kuh l, kwey-sahy-, kwah-see, -zee-] Word Origin noun Physics.

1. an entity, as an exciton or phonon, that interacts with elementary particles, but does not exist as a free particle.

Origin of quasiparticle First recorded in 1955–60; quasi- + particle