Old English mentel "a loose, sleeveless garment worn as an outer covering, falling in straight lines from the shoulders," from Latin mantellum "cloak" (source of Italian mantello, Old High German mantal, German Mantel, Old Norse mötull), perhaps from a Celtic source, or, if the Latin word is the same word as mantelum, mantelium "a cloth, hand-towel, napkin," perhaps it is from manus "hand."
Reinforced and altered 12c. by cognate Old French mantel "cloak, mantle; bedspread, cover" (Modern French manteau), also from the Latin source. Figurative sense "that which enshrouds, something that conceals, a covering" is from c. 1300. Allusive use for "symbol of literary authority or artistic pre-eminence" (by 1789) is from Elijah's mantle (II Kings ii.13). As a layer of the earth between the crust and core (though not originally distinguished from the core) it is attested from 1940. To take (originally have) the mantel (and the ring) was a symbolic act done before a bishop by a widow, indicating a vow of chastity (c. 1400).
"to look dark and menacing," also lour, from Middle English louren, luren "to frown, scowl" (early 13c.), "to lurk" (mid-15c.), from Old English *luran or from its cognates, Middle Low German luren, Middle Dutch loeren "lie in wait." The form perhaps has been assimilated to lower (v.1). Related: Lowered; lowering.
early 13c., mantelen, "to wrap or cover in a mantle," from mantle (n.) or from Old French manteler, from the noun in French. The figurative sense of "to obscure or protect by covering up" is from mid-15c. Intransitive sense of "become covered with a coating" (of liquids) is from 1620s; that of "become suffused" (as with blushes or color) is by 1707. Related: Mantled; mantling.
c. 1600, "descend, sink, grow less or lower" (intransitive), from lower (adj.), comparative of low (adj.). Transitive meaning "let down, cause to descend" attested from 1650s. Related: Lowered; lowering. In the transitive sense "to cause to descend" the older verb was low (Middle English lahghenn, c. 1200), which continued in use into the 18c.
Middle English lawar, lower, lougher, earlier lahre (c. 1200), comparative of lah "low" (see low (adj.)). As an adverb from 1540s. Lower-class is from 1772. Lower 48, "the forty-eight contiguous states of the United States of America, excluding Alaska and Hawaii," is by 1961 in an Alaska context (Hawaii actually is "lower" on the globe than all of them).
"cloak, mantle," 1670s, from French manteau "a cloak," from Old French mantel, from Latin mantellum "cloak" (see mantle (n.)).
c. 1200, "short, loose, sleeveless cloak," variant of mantle (q.v.). Sense of "movable shelter for soldiers besieging a fort" is from 1520s.
The meaning "timber or stone supporting masonry above a fireplace" is attested by 1510s; it is a shortened form of Middle English mantiltre "mantle-tree" (late 15c.) "beam of oak or some other hard wood above a fireplace or oven" (with tree in the now-obsolete sense of "beam"). But the exact meaning of mantle in that had become obscure by the 19c.
In a fire-place, the mantle or mantlepiece, may have been either a covered or chimney-piece; or the part below it to which a hanging, for the sake of making a flue for the wind to draw up the fire, was attached. The details, however, of this are uncertain. [Robert Gordon Latham, "A Dictionary of the English Language," 1882]
Mantel-clock "clock intended to sit on a mantle-shelf," is by 1824.
"cloth worn as a shawl by women in Iran," 1884, from Persian chadar "tent, mantle, scarf, veil, sheet, table-cloth."