Thumb (?), n. [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.
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Upon his thumb he had of gold a ring. Chaucer.
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Thumb band, a twist of anything as thick as the thumb. 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. 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. Shak. -- 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) (Mil.) 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. [Colloq.]
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Thumb, v. i. To play with the thumb or thumbs; to play clumsily; to thrum.
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