disk

Pluraldisks

Formsdisks, disking, disked

1. 1
   nouncountable

   A flat circular piece of metal, plastic, or other material, thin in relation to its width.

   The craftsman polished a brass disk until it gleamed under the lamp.

   Each disk was stamped with a serial number along its rim.

   Similarplate, circle

   Note

   The everyday sense, and the closest to the word's origin: Greek dískos was a circular plate made for hurling, from a verb meaning "to hurl." The same source produced discus, dish, desk and dais, so an athlete's throwing plate, a serving dish and a raised platform are all distant cousins. A coin is the model case. It is thin as well as round, and both qualities count.

2. 2
   nounabbreviationellipsis

   Ellipsis of hard disk.

   The computer would not start because the disk had failed.

   She backed up the entire disk before installing the upgrade.

   Note

   This clipped form covers two things. Strictly, a hard disk is one of the parallel magnetic platters inside a drive. In everyday use it is the whole unit with all its platters. So "the disk failed" and "back up the disk" nearly always mean the drive as a whole, not a single platter inside it.

3. 3
   nounabbreviationellipsis

   Ellipsis of floppy disk.

   He labeled each disk and stored them in a plastic case.

   Every disk held only a small amount of data by today's standards.

   Note

   Ordinary computing talk shortened the compound because the full name added nothing in context. A floppy disk was a removable medium between 2 and 8 inches across, holding anywhere from 80 KB to 240 MB. When someone speaks of old disks from 1979, it is this removable sort they mean. Context alone separates it from the hard-disk sense.

4. 4
   nouncountable

   A cushioning pad of cartilage between adjacent vertebrae of the spine.

   The MRI showed a bulging disk pressing on a nerve root.

   Years of poor posture wore down the disk between her vertebrae.

   Note

   Each disk is a fibrocartilaginous cushion with a tough outer ring around a gel-like core. It takes the load between two vertebrae and allows the spine to bend a little. In the full anatomical term it is usually spelled intervertebral disc. In speech about injury, people simply say a bulging or worn disk.

5. 5
   nounnonstandardabbreviationellipsis

   Ellipsis of optical disk. For CDs and DVDs the usual spelling is disc.

   He inserted the disk and the installer launched automatically.

   A single disk could hold an entire encyclopedia.

   Note

   For laser-read media such as CDs and DVDs, the main spelling ends in -c: optical disc. Calling them disks with a k is the nonstandard variant, though it is common in casual speech. The characteristic verb is burn, as in burning disks to back up a computer. In careful writing about optical media, prefer disc.

6. 6
   nouncountable

   A two-dimensional region consisting of all the points enclosed by a circle.

   The integral was evaluated over the unit disk.

   Every point on the boundary circle lies just outside the open disk.

   Note

   Mathematicians keep two words apart that everyday speech blurs. The circle is the boundary curve, and the disk is the whole region it encloses. An open disk contains only the points strictly inside the circle. A closed disk includes the circle itself. The unit disk, with radius one, is the standard region for integrals and for much of complex analysis.

7. 7
   nounfigurativelycountable

   Any object having the flat, round shape of a disk.

   The sun sank as a glowing red disk behind the hills.

   From above, the still lake formed a perfect blue disk.

   Similarcircle, orb, round

   Note

   Astronomy makes heavy use of this sense. A planet's or the sun's disk is its visible round face as seen from Earth, which is why Venus can be said to cut off light with its disk as it passes in front of the sun. The shape is borrowed, not the substance. A disk of this kind need not be flat or solid, only round to the eye.

8. 8
   nouncountable

   A ring- or cup-shaped swelling of a flower's receptacle or ovary that bears nectar and, less often, the stamens.

   Nectar pooled on the fleshy disk surrounding the ovary.

   In this species the stamens arise directly from the floral disk.

   Note

   Botanists apply the name even where the shape is a ring or a cup rather than a flat plate. The floral disk is a glandular outgrowth of the receptacle or ovary. It often secretes nectar that attracts pollinators, and in some species the stamens rise from it. Treat it as a structure in its own right, not simply a part of the receptacle.

9. 9
   nouncountable

   A farming implement fitted with rows of rotating concave blades that cut and turn the soil.

   He hitched the disk to the tractor and worked the stubble into the ground.

   After plowing, they ran a disk across the field to level it.

   Similarharrow

   Note

   This is short for disk harrow. The implement has rows of concave steel blades mounted on axles, and as it is dragged across a field the blades slice through crop residue and break up clods to prepare a seedbed. The name comes from the round blades. On a farm, "the disk" usually means the whole machine hitched behind a tractor.

10. 10
    verbtransitive

    To work soil by dragging a bladed harrow across it, cutting and leveling the ground.

    Before sowing, they disk the soil to break up the heavy clods.

    Many growers disk their fields twice to bury crop residue.

    Similarharrow, till, cultivate

    Note

    The farmer's verb comes straight from the bladed harrow and inflects regularly: disks, disking, disked. It often travels in a pair, "plowed and disked," naming two steps of preparing ground. That pairing runs from a 1916 Minnesota orchard report to Jerry Sullivan's 1991 prairie-restoration piece in the Chicago Reader.

11. 11
    verbtransitive

    To set a propeller's blades to zero pitch, turning them face-on to the airflow so they produce maximum drag.

    To shorten the landing roll, pilots disk the propeller on touchdown.

    Flight crews disk the blades to add drag when they need to lose speed fast.

    Oppositefeather

    Note

    Pilots borrow the shape for this sense. At zero pitch the propeller blades present their flat faces to the airstream, and the spinning propeller acts like a solid disk that creates drag. The verb works both ways: the propeller disks, or the crew disks it. It is used when slowing down quickly, such as during the landing roll.

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