c. 1300, recoveren, "to regain consciousness," also "regain health or strength after sickness, injury, etc.," from Anglo-French rekeverer (13c.), Old French recovrer "come back, return; regain health; procure, get again" (11c.), from Medieval Latin recuperare "to recover" (source of Spanish recobrar, Italian ricoverare; see recuperation).
The sense of "get (anything) back, get or regain possession or control of," literally or figuratively, after it has been lost, is attested from mid-14c. In law, "obtain by judgment or legal proceedings," late 14c. The transitive sense of "restore from sickness, restore (another) to health" is from c. 1600; that of "rescue, save from danger" is from 1610s. Related: Recovered; recovering. To recover arms (1680s) is to bring the piece from the position of "aim" to that of "ready."