An arch is a shape that resembles an upside down "U." You may find this shape in a carefully tweezed eyebrow or in the famous golden pair that make you hunger for a Big Mac.

In architecture, an arch is an opening that is often found supporting the weight of a something above it — like a bridge or a wall. In downtown St. Louis, you can visit the Gateway Arch — a freestanding catenary arch that is 630 feet tall and 630 feet wide. As a verb, arch means to make an arch-like shape. "She stretched her back by arching it into a backbend." As an adjective, arch can describe something mischievous or sly: "He teased his friend with an arch comment about his shyness around girls."

Definitions of arch
  1. noun
    (architecture) a masonry construction (usually curved) for spanning an opening and supporting the weight above it
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    abutment arch
    an arch supported by an abutment
    broken arch
    an arch with a gap at the apex; the gap is usually filled with some decoration
    camber arch
    an arch with a straight horizontal extrados and a slightly arched intrados
    corbel arch
    (architecture) an arch constructed of masonry courses that are corbelled until they meet
    flat arch, straight arch
    an arch with mutually supporting voussoirs that has a straight horizontal extrados and intrados
    pier arch
    an arch supported on piers
    pointed arch
    an arch with a pointed apex; characteristic of Gothic architecture
    proscenium arch
    the arch over the opening in the proscenium wall
    rampant arch
    an arch whose support is higher on one side than on the other
    round arch
    an arch formed in a continuous curve; characteristic of Roman architecture
    rowlock arch
    an arch that is formed with more than one concentric row of voussoirs
    safety arch
    an undecorated arch that is included in order to strengthen or support a construction
    scoinson arch, sconcheon arch
    an arch that supports part of the wall
    segmental arch
    a shallow arch; an arch that is less than a semicircle
    shouldered arch
    an arch consisting of a horizontal lintel supported at each end by corbels that project into the aperture
    diminished arch, scheme arch, skeen arch, skene arch
    an arch whose height is less than half its width
    skew arch
    an arch whose jambs are not at right angles with the face
    a small arch built across the interior angle of two walls (usually to support a spire)
    trimmer arch
    an arch built between trimmers in a floor (to support the weight of a hearth)
    triumphal arch
    a monumental archway; usually they are built to commemorate some notable victory
    Tudor arch, four-centered arch
    a low elliptical or pointed arch; usually drawn from four centers
    bell arch
    a round arch resting on corbels
    drop arch
    a blunt pointed arch drawn from two centers within the span
    Gothic arch
    a pointed arch; usually has a joint (instead of a keystone) at the apex
    Moorish arch, horseshoe arch
    a round arch that widens before rounding off
    keel arch, ogee arch
    a pointed arch having an S-shape on both sides
    Roman arch, semicircular arch
    a round arch drawn from a single center
    basket-handle arch, three-centered arch
    a round arch whose inner curve is drawn with circles having three centers
    trefoil arch
    a pointed arch having cusps in the intrados on either side of the apex
    trumpet arch
    a conical squinch
    type of:
    construction, structure
    a thing constructed; a complex entity constructed of many parts
  2. noun
    a passageway under a curved masonry construction
    “they built a triumphal arch to memorialize their victory”
    synonyms: archway
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    type of:
    entrance, entranceway, entree, entry, entryway
    something that provides access (to get in or get out)
  3. noun
    a curved shape in the vertical plane that spans an opening
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    type of:
    curve, curved shape
    the trace of a point whose direction of motion changes
  4. noun
    a curved bony structure supporting or enclosing organs (especially the inner sides of the feet)
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    metatarsal arch
    the short lateral arch formed by the heads of the metatarsals
    the arch of the foot
    pectoral arch, shoulder girdle
    the bony arch formed by the collarbones and shoulder blades in humans
    haemal arch, hemal arch
    a structure arising ventrally from a vertebral centrum and enclosing the caudal blood vessels
    neural arch, vertebral arch
    a structure arising dorsally from a vertebral centrum and enclosing the spinal cord
    fallen arch, sunken arch
    an instep flattened so the entire sole rests on the ground
    type of:
    skeletal structure
    any structure created by the skeleton of an organism
  5. verb
    form an arch or curve
    “her back arches
    synonyms: arc, curve
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    curve upward in the middle
    type of:
    bend, flex
    form a curve
  6. adjective
    (used of behavior or attitude) characteristic of those who treat others with condescension
    synonyms: condescending, patronising, patronizing
    of or characteristic of high rank or importance
  7. adjective
    naughtily or annoyingly playful
    synonyms: impish, implike, mischievous, pixilated, prankish, puckish, wicked
    full of fun and high spirits
  8. adjective
    expert in skulduggery
    “an arch criminal”
    having or showing or requiring special skill
Word Family

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