early 15c., from Old French recliner "rest, lay; bend, lean over" (13c.) and directly from Latin reclinare "to bend back, to lean back; cause to lean," from re- "back, against" (see re-) + clinare "to bend," from PIE *klein-, suffixed form of root *klei- "to lean." Related: Reclined; reclining.
Recline is always as strong as lean, and generally stronger, indicating a more completely recumbent position, and approaching lie. [Century Dictionary]