meson vs k-meson

meson and k-meson both are nouns.

Word	Noun	Adjective	Verb	Adverb
meson	Yes	No	No	No
k-meson	Yes	No	No	No

As nouns, k-meson is a hyponym of meson; that is, k-meson is a word with a more specific, narrower meaning than meson:

meson: an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0
k-meson: an unstable meson produced as the result of a high-energy particle collision

Other hyponyms of meson include b-meson, J particle, psi particle, K particle, kaon, kappa-meson, pi-meson, pion.

meson (noun)	k-meson (noun)
an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0	an unstable meson produced as the result of a high-energy particle collision