A meson is a sub-atomic, non-elementary particle composed of a quark and an anti-quark.
All mesons are unstable and fluctuations in the meson field were observed at the terminus of the Barzan wormhole, creating instability in the wormhole and causing its terminus to shift between the Delta Quadrant and the Denkiri Arm of the Gamma Quadrant. (TNG: "The Price")
While scanning for the crash landed runabout USS Yangtzee Kiang in the Gamma Quadrant, Lieutenant Jadzia Dax noted that the warp eddy had traces of meson particle emissions, which made it a Starfleet power reactor. (DS9: "Battle Lines")
According to the script for "Battle Lines", meson was pronounced as "MAY-zon". [1]
Michael Okuda and Rick Sternbach suggested that a "meson wave collimator" could be used to detect the Bajoran wormhole in a line cut from DS9: "Emissary". Michael Piller used "field density compensator" instead. The line was retained in the novelization. (The Making of Star Trek: Deep Space Nine)