Definition of "interneuron"

The interneuron is a major neuroarchitectural element within the arthropod central nervous system, both in terms of numbers and diversity of form.

1995, G. S. Boyan, J. L. D. Williams, “Lineage analysis as a diagnostic tool in the insect central nervous system: Bringing order to interneurons”, in O. Breidbach, Wolfram Kutsch, editors, The Nervous Systems of Invertebrates: An Evolutionary and Comparative Approach, page 273

Another important difference between interneuron and pyramidal cell spines is the number of synaptic boutons. The spines of interneurons are covered by numerous excitatory synaptic boutons (four to eight synapses per spine).

2007, Nelson Spruston, Chris McBain, “5: Structural and Functional Properties of Hippocampal Neurons”, in Per Andersen, Richard Morris David Amaral, Tim Bliss, John O'Keefe, editors, The Hippocampus Book, page 184

Embedded within these spinal circuits are local interneurons. An interneuron is generally defined as a neuron that only synapses onto other neurons. In the central nervous system, interneurons are considered to be the neurons that have local rather than long-distance projections.

2011, Susan A. Duchars, “8: Spinal Interneurons in the Control of Autonomic Function”, in Ida J. Llewellyn-Smith, Anthony J. M. Verberne, editors, Central Regulation of Autonomic Functions, 2nd edition, page 140