cline n.

in early use also encline, c. 1300, "to bend or bow toward," from Old French encliner "to lean, bend, bow down," from Latin inclinare "to cause to lean; bend, incline, turn, divert," from in- "into, in, on, upon" (from PIE root *en "in") + clinare "to bend" (from PIE *klein-, suffixed form of root *klei- "to lean"). Metaphoric sense of "have a mental disposition toward" is early 15c. in English (but existed in classical Latin). Related: Inclined; inclining.

Proto-Indo-European root meaning "to lean."

It forms all or part of: acclivity; anticline; clemency; client; climate; climax; cline; clinic; clinical; clino-; clitellum; clitoris; decline; declivity; enclitic; heteroclite; incline; ladder; lean (v.); lid; low (n.2) "small hill, eminence;" matroclinous; patroclinous; polyclinic; proclitic; proclivity; recline; synclinal; thermocline.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit srayati "leans," sritah "leaning;" Old Persian cay "to lean;" Lithuanian šlyti "to slope," šlieti "to lean;" Latin clinare "to lean, bend," clivus "declivity," inclinare "cause to bend," declinare "bend down, turn aside;" Greek klinein "to cause to slope, slant, incline;" Old Irish cloin "crooked, wrong;" Middle Irish cle, Welsh cledd "left," literally "slanting").