Definition of "gluon"

Naive realism might ask today: Tell me what space is in itself, not in terms of other things. Tell me what a gluon is at bottom, or a neutrino, or a charge.

1992 November, George Zebrowski, Marvin Mattelson, “The Enigma of Distance”, in Omni, volume 15, number 2, page 80

The so-called spin crisis has had important effects beyond simply confronting theorists with a particularly sharp challenge to their incomplete understanding of quantum chromodynamics, the underlying field theory of quarks and the gluons that mediate their strong interactions.

1995 September, Robert Jaffe, “Where Does the Proton Really Get Its Spin?”, in Physics Today, volume 48, number 9, page 24

Lattice QCD explores the particle realm by taking a different tack. It simulates quark and gluon behaviors by applying the full QCD theory to a tiny grid like facsimile of the space-time in which particles actually interact.

2004 September 7, Peter Weiss, “Starting from Square One”, in Science News, volume 166, number 6, pages 90–1