-on1

1.
a suffix used in the names of subatomic particles (gluon; meson; neutron), quanta (graviton), and other minimal entities or components (cistron; codon; magneton; photon).
Origin
probably extracted from ion; cf. proton

-on2

1.
a suffix used in the naming of inert gaseous elements:
neon.
Origin
≪ Greek -on, neuter of -os adj. ending
British Dictionary definitions for -on

-on

suffix
1.
indicating a chemical substance: interferon, parathion
2.
(in physics) indicating an elementary particle or quantum: electron, photon
3.
(in chemistry) indicating an inert gas: neon, radon
4.
(in biochemistry) a molecular unit: codon, operon
Word Origin
from ion
Word Origin and History for -on

subatomic particle suffix, from ion.

-on in Medicine

-on 1
suff.

  1. A subatomic particle: neutron.

  2. A unit: photon.

  3. A basic hereditary unit: codon.

-on 2
suff.
Inert gas: radon.

-on 3
suff.
A chemical compound that is not a ketone or a compound that contains oxygen in a carbonyl group: parathion.