thumb

Webster's Dictionary (1913)

Origin: OE. thombe, thoumbe, þume, AS. þūma; akin to OFries. thūma, D. duim, G. daumen, OHG. dūmo, Icel. þumall, Dan. tommelfinger, Sw. tumme, and perhaps to L. tumere to swell. √56. Cf. Thimble, Tumid.

The short, thick first digit of the human hand, differing from the other fingers in having but two phalanges; the pollex. See Pollex.

Upon his thumb he had of gold a ring.— Geoffrey Chaucer

Thumb band, a twist of anything as thick as the thumb. John Mortimer — Thumb blue, indigo in the form of small balls or lumps, used by washerwomen to blue linen, and the like. — Thumb latch, a door latch having a lever formed to be pressed by the thumb. — Thumb mark. (a) The mark left by the impression of a thumb, as on the leaves of a book. Henry W. Longfellow (b) The dark spot over each foot in finely bred black and tan terriers. — Thumb nut, a nut for a screw, having wings to grasp between the thumb and fingers in turning it; also, a nut with a knurled rim for the same perpose. — Thumb ring, a ring worn on the thumb. William Shakespeare — Thumb stall. (a) A kind of thimble or ferrule of iron, or leather, for protecting the thumb in making sails, and in other work. (b) Military A buckskin cushion worn on the thumb, and used to close the vent of a cannon while it is sponged, or loaded. — Under one's thumb, completely under one's power or influence; in a condition of subservience. colloquial

1. To handle awkwardly. Dr. Samuel Johnson

2. To play with the thumbs, or with the thumbs and fingers; as, to thumb over a tune.

3. To soil or wear with the thumb or the fingers; to soil, or wear out, by frequent handling; also, to cover with the thumb; as, to thumb the touch-hole of a cannon.

He gravely informed the enemy that all his cards had been thumbed to pieces, and begged them to let him have a few more packs.— Thomas Babington Macaulay

To play with the thumb or thumbs; to play clumsily; to thrum.

Webster’s Revised Unabridged Dictionary (1913), from GCIDE 0.54

Free On-line Dictionary of Computing

<processor> An extension to the Advanced RISC Machine architecture, announced on 06 March 1995 by Advanced RISC Machines Ltd. By identifying the critical subset of the ARM instruction set and encoding it into 16 bits, ARM has succeeded in reducing typical program size by 30-40% from ARM's already excellent code density. Since this Thumb instruction set uses less memory for program storage, cost is further reduced.

All Thumb-aware processor cores combine the capability to execute both the 32-bit ARM and the 16-bit Thumb instruction sets. Careful design of the Thumb instructions allow them to be decompressed into full ARM instructions transparently during normal instruction decoding without any performance penalty. This differs from other 32-bit processors, like the Intel 486SX, with a 16-bit data bus, which require two 16-bit memory accesses to execute every 32-bit instruction and so halve performance.

The patented Thumb decompressor has been carefully designed with only a small amount of circuitry additional to the existing instruction decoder, so chip size and thus cost do not significantly increase. Designers can easily interleave fast ARM instructions (for performance critical parts of a program) with compact Thumb code to save memory.

(1995-03-14)

<jargon> The slider or "bubble" on a window system scrollbar. So called because moving it allows you to browse through the contents of a text window in a way analogous to thumbing through a book. [Jargon File]

(1995-03-14)

The Jargon File

The slider on a window-system scrollbar. So called because moving it allows you to browse through the contents of a text window in a way analogous to thumbing through a book.