1895 Jrnl. Chem. Soc. 68 i. 314 The term nucleon is suggested for compounds, such as phosphorcarnic acid, which are allied to the nucleïns but contain peptone instead of albumin.

1905 W. H. Howell Text-bk. Physiol. ii. 60 The discoverer of nucleon has attributed to it a very great physiological importance, as a source of energy to the muscle, and as an efficient means of transportation of iron, calcium, [etc.]... It must be stated, however, that there still remains some doubt as to the chemical individuality of the nucleon or the nucleons.

1921 Physiol. Abstr. 6 477 Nucleon is a mixture of which the chief constituent is denatured protein.

1923 D. L. Hammick tr. J. B. Perrin Atoms (ed. 2) App. 222 If we represent the hydrogen nucleus or positive protoatom by h and the corpuscle or negative protoatom by β we may say that all matter is made up of protoatoms h and β... The negative protoatom may be called the corpuscle and the positive protoatom the nucleon. [Note] Suggested by P. Auger. Proton has also been suggested.

1939 F. J. Belinfante Theory of Heavy Quanta (Doctoral thesis, Leiden Univ.) 40 The interaction of the heavy quanta with the heavy particles (the proton-neutron, or ‘nuclon’, as we shall call it briefly).

1940 W. Pauli & F. J. Belinfante in Physica 7 179 The particle that is a proton in its charged state and a neutron in its neutral state, we have called a nuclon.

1941 C. Møller in Physical Rev. 59 323/2 Following the original proposal of Belinfante, the writer has..used the word ‘nuclon’ as a common notation for..neutrons and protons. In the meantime, however, it has been pointed out to me that, since the root of the word nucleus is ‘nucle’, the notation ‘nucleon’ would from a philological point of view be more appropriate.

1952 Sci. News 23 28 It seems that each nucleon (a general name for either proton or neutron) cannot interact with all the other particles in the nucleus, but only with its neighbours.

1968 M. S. Livingston Particle Physics v. 97 With both protons bombarding a high-Z target, to create a nucleon-antinucleon pair.., the threshold kinetic energy must be 5·4 GeV.

1989 C. Isham in P. Davies New Physics v. 87/2 With the introduction of the SU(2) iso-spin symmetry, the proton and neutron can be regarded as two states of a ‘nucleon’.