| tactile sense | 1. To come in contact with; to hit or strike lightly against; to extend the hand, foot, or the like, so as to reach or rest on. "Him thus intent Ithuriel with his spear Touched lightly." (Milton) 2. To perceive by the sense of feeling. "Nothing but body can be touched or touch." (Greech) 3. To come to; to reach; to attain to. "The god, vindictive, doomed them never more- Ah, men unblessed! to touch their natal shore." (Pope) 4. To try; to prove, as with a touchstone. "Wherein I mean to touch your love indeed." (Shak) 5. To relate to; to concern; to affect. "The quarrel toucheth none but us alone." (Shak) 6. To handle, speak of, or deal with; to treat of. "Storial thing that toucheth gentilesse." (Chaucer) 7. To meddle or interfere with; as, I have not touched the books. 8. To affect the senses or the sensibility of; to move; to melt; to soften. "What of sweet before Hath touched my sense, flat seems to this and harsh." (Milton) "The tender sire was touched with what he said." (Addison) 9. To mark or delineate with touches; to add a slight stroke to with the pencil or brush. "The lines, though touched but faintly, are drawn right." (Pope) 10. To infect; to affect slightly. 11. To make an impression on; to have effect upon. "Its face . . . So hard that a file will not touch it." (Moxon) 12. To strike; to manipulate; to play on; as, to touch an instrument of music. "[They] touched their golden harps." (Milton) 13. To perform, as a tune; to play. "A person is the royal retinue touched a light and lively air on the flageolet." (Sir W. Scott) 14. To influence by impulse; to impel forcibly. " No decree of mine, . . . [to] touch with lightest moment of impulse his free will," 15. To harm, afflict, or distress. "Let us make a covenant with thee, that thou wilt do us no hurt, as we have not touched thee." (Gen. Xxvi. 28, 29) 16. To affect with insanity, especially in a slight degree; to make partially insane; rarely used except in the past participle. "She feared his head was a little touched." (Ld. Lytton) 17. <geometry> To be tangent to. See Tangent. 18. To lay a hand upon for curing disease. To touch a sail, to keep the ship as near the wind as possible. To touch up, to repair; to improve by touches or emendation. Origin: F. Toucher, OF. Touchier, tuchier; of Teutonic origin; cf. OHG. Zucchen, zukken, to twitch, pluck, draw, G. Zukken, zukken, v. Intens. Fr. OHG. Ziohan to draw, G. Ziehen, akin to E. Tug. See Tuck, Tug, and cf. Tocsin, Toccata. 1. The act of touching, or the state of being touched; contact. "Their touch affrights me as a serpent's sting." (Shak) 2. <physiology> The sense by which pressure or traction exerted on the skin is recognised; the sense by which the properties of bodies are determined by contact; the tactile sense. See Tactile sense, under Tactile. "The spider's touch, how exquisitely fine." (Pope) Pure tactile feelings are necessarily rare, since temperature sensations and muscular sensations are more or less combined with them. The organs of touch are found chiefly in the epidermis of the skin and certain underlying nervous structures. 3. Act or power of exciting emotion. "Not alone The death of Fulvia, with more urgent touches, Do strongly speak to us." (Shak) 4. An emotion or affection. "A true, natural, and a sensible touch of mercy." (Hooker) 5. Personal reference or application. "Speech of touch toward others should be sparingly used." (Bacon) 6. A stroke; as, a touch of raillery; a satiric touch; hence, animadversion; censure; reproof. "I never bare any touch of conscience with greater regret." (Eikon Basilike) 7. A single stroke on a drawing or a picture. "Never give the least touch with your pencil till you have well examined your design." (Dryden) 8. Feature; lineament; trait. "Of many faces, eyes, and hearts, To have the touches dearest prized." (Shak) 9. The act of the hand on a musical instrument; bence, in the plural, musical notes. "Soft stillness and the night Become the touches of sweet harmony." (Shak) 10. A small quantity intermixed; a little; a dash. "Eyes La touch of Sir Peter Lely in them." (Hazlitt) "Madam, I have a touch of your condition." (Shak) 11. A hint; a suggestion; slight notice. "A small touch will put him in mind of them." (Bacon) 12. A slight and brief essay. "Print my preface in such form as, in the booksellers' phrase, will make a sixpenny touch." (Swift) 13. A touchstone; hence, stone of the sort used for touchstone. " Now do I play the touch." "A neat new monument of touch and alabaster." (Fuller) 14. Hence, examination or trial by some decisive standard; test; proof; tried quality. "Equity, the true touch of all laws." (Carew) "Friends of noble touch ." (Shak) 15. The particular or characteristic mode of action, or the resistance of the keys of an instrument to the fingers; as, a heavy touch, or a light touch, also, the manner of touching, striking, or pressing the keys of a piano; as, a legato touch; a staccato touch. 16. The broadest part of a plank worked top and but (see Top and but, under Top,), or of one worked anchor-stock fashion (that is, tapered from the middle to both ends); also, the angles of the stern timbers at the counters. 17. That part of the field which is beyond the line of flags on either side. 18. A boys' game; tag. In touch, outside of bounds. To be in touch, to be in contact, or in sympathy. To keep touch. To be true or punctual to a promise or engagement; hence, to fulfill duly a function. "My mind and senses keep touch and time." (Sir W. Scott) To keep in contact; to maintain connection or sympathy;-with with or of. Touch and go, a phrase descriptive of a narrow escape. True as touch (i.e, touchstone), quite true. Origin: Cf. F. Touche. See Touch. Source: Websters Dictionary (01 Mar 1998) |
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| Abbe theory of image formation | <optics, physics> Abbe's theory is based on the fact that a non-self-luminous particle, which is illuminated by an extraneous source, gives rise to diffracted light rays, in addition to the dioptric pencil. He stated that to form a good microscopical image as many of the diffracted rays as possible should be intercepted by the objective. With closely ruled lines, his theory is easily demonstrated by observing the back lens of the objective, for here the diffracted rays can be observed directly if the aperture diaphragm is closed. It can be shown that, when the illumination is arranged to exclude the diffracted images, resolution is lost. (11 Mar 1998) |
| accidental image | Continuation of visual impression after cessation of stimuli causing the original image. (12 Dec 1998) |
| body image | A term for the concept which each individual has of his own body as an object in and bound by space, independently and apart from all other objects. (12 Dec 1998) |
| radiographic image enhancement | Improvement in the quality of an X-ray image by use of an intensifying screen, tube, or filter and by optimum exposure techniques. Digital processing methods are often employed. (12 Dec 1998) |
| radiographic image interpretation, computer-assisted | Computer systems or networks designed to provide radiographic interpretive information. (12 Dec 1998) |
| real image | An image formed by the convergence of the actual rays of light from an object. Synonym: inverted image. (05 Mar 2000) |
| catatropic image | <ophthalmology, physiology> The two images formed by the anterior and posterior surfaces of the cornea and the two images formed by the anterior and posterior surfaces of the lens. Synonym: catatropic image, Purkinje images, Sanson's images. (05 Mar 2000) |
| virtual image | <microscopy> Such as seen in a mirror or through a magnifier. A virtual image has no real existence in space as does a real image from a lens. It does have a definite location, however, caused by the angles of divergence of the rays received by the eye. This can be shown by the common school experiment of placing a pin coincident with its mirror image behind a sheet of glass acting as a partial mirror. Its location can also be placed in design by extrapolating backwards to a focus. If a magnifier is used as it should be, with the object at its focus, the virtual image is at infinity. The same is true for a microscope focused for the relaxed eye. See: distance of virtual image. (05 Aug 1998) |
| visual image | A collection of foci corresponding to all the luminous points of an object. (05 Mar 2000) |
| retinal image | A real image formed on the retina. (05 Mar 2000) |
| mental image | A picture of an object not present, produced in the mind by memory or imagination. (05 Mar 2000) |
| phase image | A magnetic resonance image showing only phase shift information, to detect motion. (05 Mar 2000) |
| mirror image | A representation of an object or part thereof as its reflected image in a glass mirror. (05 Mar 2000) |
| mirror-image cell | A cell whose nuclei have identical features and are placed in the cytoplasm in similar fashion, a binucleate form of Reed-Sternberg cell often found in Hodgkin's disease; the twin nuclei are disposed in relation to an imaginary plane between them like a single nucleus together with its image in a mirror. (05 Mar 2000) |