1550s, "hedge, fence," also "an embankment, a dam" (a sense probably influenced by mount (n.)), a word of obscure origin. The relationship between the noun and the verb is uncertain.

Commonly supposed to be from Middle English mounde "the hand; guardianship, power," from Old English mund (cognate with Latin manus), but this is not certain (OED discounts it on grounds of sense). Perhaps it is a confusion of the native word and Middle Dutch mond "protection," used in military sense for fortifications of various types, including earthworks.

From 1726 as "artificial elevation of earth" (as over a grave); 1810 as "natural low elevation." As the place where the pitcher stands on a baseball field, from 1912. Mound-builder "one of the prehistoric race of the Mississippi Valley that erected extensive earthworks" is by 1838.

In Middle English mounde also meant "the world," from Old French monde, from Latin mundus (see mundane).

1510s, "to enclose with a fence;" c. 1600 as "to enclose or fortify with an embankment;" see mound (n.). From 1859 as "to heap up." Related: Mounded; mounding.

ancient burial mound, 1680s, from Latin tumulus "hillock, heap of earth, mound" (see tomb).

c. 1300, mote "a mound, a hill" (a sense now obsolete); late 14c., "ditch or deep trench dug round the rampart of a castle or other fortified place," from Old French mote "mound, hillock, embankment; castle built on a hill" (12c.; Modern French motte) and directly from Medieval Latin mota "mound, fortified height," a word of unknown origin, perhaps from Gaulish mutt, mutta.

The sense shifted in Norman French from the castle mound to the ditch dug around it. For a similar evolution, compare ditch (n.) and dike. As a verb, "to surround with a moat," early 15c. Related: Moated.

also how, "artificial burial mound," 1660s, from a local word in northern England for a hill or hillock, from a Middle English use of Old Norse haugr "mound; cairn," perhaps from the root of high (adj.).

also anthill, "mound of dirt formed by ants in building their nest," late 13c., from ant + hill (n.).

sand-bar joining an island to the mainland, 1899, from Italian tombolo "sand dune," from Latin tumulus "hillock, mound, heap of earth" (see tomb).

1727, from Latin tumulosus "full of hills," from tumulus "hill, mound, heap of earth" (see tumulus).

late 14c., hilloc "small hill, mound or heap of earth" (c. 1200 as a surname), from hill (n.) + Middle English diminutive suffix -oc.

1530s, "gather into a heap or mass" (transitive), from Latin cumulatus "heaped, increased, augmented," past participle of cumulare "to heap," from cumulus "mound, heap" (from suffixed form of PIE root *keue- "to swell"). Related: Cumulated; cumulating; cumulant.