connection is the state of being joined, or the thing that joins — a physical or logical link between objects, a relation between ideas, and the felt sense of being in genuine contact with another person.
The word covers an unusually wide span for a single form. It names the act of connecting, recorded around 1600; anything that performs the joining, by 1741; the circle of people with whom one has dealings, by 1767, which is where the plural "connections" as social capital comes from; the meeting of one train, flight, or bus with the next, by 1862; and, in twentieth-century slang, a supplier of drugs, by 1934. Networked computing added the sense most used today, in which a connection is a session held open between two machines.
English took the word in the late fourteenth century, spelled conneccion and later connexioun, from Old French connexion and Latin connexionem, "a binding or joining together," from conectere — com-, "together," with nectere, "to bind, tie," from a Proto-Indo-European root meaning to bind. The connexion spelling was standard for centuries and shifted to connection in American English through the mid-eighteenth century by analogy with connect, affection, and direction; connexion survives in some British legal and ecclesiastical usage.
In its human sense connection is narrower than acquaintance and broader than 📝intimacy: it describes contact in which both parties are actually reached, without requiring the sustained mutual disclosure intimacy implies. It differs from a relationship, which is a durable structure that connection may or may not be present within, and from communication, which is the channel rather than what crosses it — the distinction 📝What We're Missing With Human Connection turns on.