The word reply was first used as noun in the middle of the sixteenth century, but it was used as a verb for over 150 years prior to that. Usage peaked in 1850 but has recently started rebounding due to a new Internet-related meaning. The word is taken from French replier, with the same meaning. That comes from Latin replicare, which meant something more like "repeat", because you're sort of repeating communication with the person you're replying to. Replicare is also the etymon of replicate, which makes even more sense when we consider the literal translation of replicare: "fold again". When something is folded, it becomes two, which is both repeated and replicated. Replicare contains the prefix re-, meaning "again", and the root is plicare, "fold". Through Proto-Italic, that derives from Proto-Indo-European plek, "to plait".
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.