You enguire about the introduction of the term "synapse"; it happened thus. - M[ichael] Foster had asked me to get on with the Nervous System part (Part iii) of a new Edition of his 'Textb. of Physiol.' for him. I had begun it, and had not got far with it before I felt the need of some name to call the junction between nerve-cell & nerve-cell [because that place of junction now entered physiology as carrying functional importance]. I wrote him of my difficulty, & my wish to introduce a specific name. I suggested using syndesm. He consulted his Trinity friend Varrall, the Euripeidean scholar, about, & Verall suggested "synapse", & as that yields a better adjectival form, it was adopted for the book.
24 April 2011
How The Synapse Got Its Name
In his Creating Modern Neuroscience: The Revolutionary 1950s Gordon Shepherd quotes a letter from Charles Sherrington to John Fulton that describes how Sherrington named the junction: