late 14c., conneccion, "state or fact of being connected," also connexioun (in this spelling from mid-15c.), from Old French connexion, from Latin connexionem (nominative connexio) "a binding or joining together," from *connexare, frequentative of conectere "to fasten together, to tie, join together," from assimilated form of com "together" (see con-) + nectere "to bind, tie" (from PIE root *ned- "to bind, tie").
Meaning "act of connecting" is from c. 1600; sense of "anything that connects" is from 1741. As "circle of persons with whom one is brought into more or less intimate relations" is from 1767. Meaning "the meeting of one means of travel with another" is from 1862. Sense of "supplier of narcotics" is attested by 1934.
also inflexion, early 15c., from Latin inflexionem (nominative inflexio) "a bending, inflection, modification," noun of action from past participle stem of inflectere "to bend in, to change" (see inflect). For spelling, see connection. Grammatical sense "variation by declension or conjugation" is from 1660s; pronunciation sense "modulation of the voice" is from c. 1600.
"Derivation" can be defined as the process by which lexical items belonging to different word-classes are drawn from given bases. Derivation must be distinguished from inflexion, by which different paradigmatic forms are created from given stems. Inflexion describes plural formations, forms of comparison, etc. Inflexion processes do not change the word-class to which the lexical item under consideration belongs. [Alfred Bammesberger, "English Etymology," Heidelberg, Carl Winter, 1984]
plural synapses, 1895 in cellular biology, Modern Latin, from Greek synapsis "connection, junction" (see synapse).