late 14c., replicacioun, "an answer, a verbal response;" also, specifically in law, "a rejoinder, legal reply" (third step in the pleadings in a common-law action), from Anglo-French replicacioun, Old French replicacion "reply, answer," from Latin replicationem (nominative replicatio) "a reply, repetition, a folding back," noun of action from past-participle stem of replicare "to repeat, reply.

This is etymologically "to fold back," from re- "back, again" (see re-) + plicare "to fold" (from PIE root *plek- "to plait"). The meaning "a copy, reproduction" is recorded by 1690s. The sense of "process by which genetic material copies itself" is from 1948.

early 15c. (Chauliac), replicaten, "repeat," from Late Latin replicatus, past participle of replicare "to reply, repeat," in classical Latin "fold back, fold over, bend back," from re- "back, again" (see re-) + plicare "to fold" (from PIE root *plek- "to plait").

Meaning "to copy, reproduce, make a replica of" is from 1882, a back-formation from replication. The scientific sense of "repeat (an experiment) and get a consistent result" is by 1923. Genetic sense is recorded from 1957. Related: Replicated; replicating; replicative.

Proto-Indo-European root meaning "to plait." It is an extended form of root *pel- (2) "to fold."

It forms all or part of: accomplice; application; apply; complex; complexion; complicate; complication; complicity; deploy; display; duplex; duplicate; duplicity; employ; explicate; explicit; exploit; flax; implex; implicate; implication; implicit; imply; multiply; perplex; perplexity; plait; plash (v.2) "to interlace;" pleat; -plex; plexus; pliable; pliant; plie; plight (n.1) "condition or state;" ply (v.1) "work with, use;" ply (v.2) "to bend; ply (n.) "a layer, fold;" replica; replicate; replication; reply; simplex; splay; triplicate.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit prasna- "turban;" Greek plekein "to plait, braid, wind, twine," plektos "twisted;" Latin plicare "to lay, fold, twist," plectere (past participle plexus) "to plait, braid, intertwine;" Old Church Slavonic plesti "to braid, plait, twist," Russian plesti; Gothic flahta "braid;" Old Norse fletta, Old High German flehtan "to plait;" Old English fleax "cloth made with flax, linen."

mid-15c., in law, "the defendant's answer to the plaintiff's replication" (the fourth stage in the pleadings in an action at common law), from Old French noun use of rejoindre "to answer to a legal charge" (see rejoin (v.2)). For noun use of infinitive in French law terms, see waiver.