n.
Pronunciation: ' me- ˌ zän, ' m ā -, ' m ē -, - ˌ sän
Function: noun
Etymology: International Scientific Vocabulary mes- + 2 -on
Date: 1939
: any of a group of fundamental particles (as the pion and kaon) made up of a quark and an antiquark that are subject to the strong force and have zero or an integer number of quantum units of spin
– me · son · ic \ me- ' zä-nik, m ā -, m ē -, - ' sä- \ adjective