| undulation | 1. The act of undulating; a waving motion or vibration; as, the undulations of a fluid, of water, or of air; the undulations of sound. 2. A wavy appearance or outline; waviness. 3. The tremulous tone produced by a peculiar pressure of the finger on a string, as of a violin. The pulsation caused by the vibrating together of two tones not quite in unison; called also beat. 4. <physics> A motion to and fro, up and down, or from side to side, in any fluid or elastic medium, propagated continuously among its particles, but with no translation of the particles themselves in the direction of the propagation of the wave; a wave motion; a vibration. Origin: Cf. F. Ondulation. Source: Websters Dictionary (01 Mar 1998) |
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| undulatory | Moving in the manner of undulations, or waves; resembling the motion of waves, which successively rise or swell rise or swell and fall; pertaining to a propagated alternating motion, similar to that of waves. <optics> Undulatory theory, or Wave theory (of light), that theory which regards its various phenomena as due to undulations in an ethereal medium, propagated from the radiant with immense, but measurable, velocities, and producing different impressions on the retina according to their amplitude and frequency, the sensation of brightness depending on the former, that of colour on the latter. The undulations are supposed to take place, not in the direction of propagation, as in the air waves constituting sound, but transversely, and the various phenomena of refraction, polarization, interference, etc, are attributable to the different affections of these undulations in different circumstances of propagation. It is computed that the frequency of the undulations corresponding to the several colours of the spectrum ranges from 458 millions of millions per second for the extreme red ray, to 727 millions of millions for the extreme violet, and their lengths for the same colours, from the thirty-eight thousandth to the sixty thousandth part of an inch. The theory of ethereal undulations is applicable not only to the phenomena of light, but also to those of heat. Origin: Cf. F. Ondulatoire. Source: Websters Dictionary (01 Mar 1998) |
| undulipodium | A flexible whiplike intracellular extension of many eukaryotic cells, with a characteristic nine-fold symmetry, an arrangement of nine paired peripheral microtubules and one central pair, often termed 9 + 2 symmetry; it appears to grow out from a basal body (kinetosome) in the cell and is a fundamental component of the eukaryotic cell. Both the cilium and the eukaryotic flagellum (not the bacterial flagellum which lacks the 9 + 2 pattern) are considered undulipodium. Origin: LL. Undulo, to move in waves, fr. L. Unda, wave, + Mod.L. Podium, fr. G. Podion, dim. Of pous, foot (05 Mar 2000) |
| undulose extinction | <microscopy> Nonuniform extinction of a substance between crossed polars. The areas of complete extinction move progressively with a fanlike motion across the surface of the substance as the stage is rotated. (05 Aug 1998) |
| unearth | To drive or draw from the earth; hence, to uncover; to bring out from concealment; to bring to light; to disclose; as, to unearth a secret. "To unearth the roof of an old tree." (Wordsworth) Origin: 1st pref. Un- + earth. Source: Websters Dictionary (01 Mar 1998) |
| unedited footage | Untitled raw motion picture and video footage which has not been edited or assembled into a finished work. (moving image materials: genre terms, 1988) (12 Dec 1998) |
| unemployment | The state of not being engaged in a gainful occupation. (12 Dec 1998) |
| unequal | 1. Not equal; not matched; not of the same size, length, breadth, quantity, strength, talents, acquirements, age, station, or the like; as, the fingers are of unequal length; peers and commoners are unequal in rank. 2. Ill balanced or matched; disproportioned; hence, not equitable; partial; unjust; unfair. "Against unequal arms to fight in pain." (Milton) "Jerome, a very unequal relator of the opinion of his adversaries." (John Worthington) "To punish me for what you make me do Seems much unequal." (Shak) 3. Not uniform; not equable; irregular; uneven; as, unequal pulsations; an unequal poem. 4. Not adequate or sufficient; inferior; as, the man was unequal to the emergency; the timber was unequal to the sudden strain. 5. <botany> Not having the two sides or the parts symmetrical. Origin: Cf. Inequal. Source: Websters Dictionary (01 Mar 1998) |
| unequal cleavage | Cleavage producing blastomeres of different sizes at the two poles. (05 Mar 2000) |
| unequal crossing over | <cell biology> Crossing over between homologous chromosomes that are not precisely paired, resulting in nonreciprocal exchange of material and chromosomes of unequal length. Favoured in regions containing tandemly repeated sequences. (18 Nov 1997) |
| unequal pulse | Differing strength of pulse in the same artery between the right and left of the circulation. (05 Mar 2000) |
| unequal retinal image | A condition in which the ocular image of an object as seen by one eye differs in size and shape from that seen by the other. (12 Dec 1998) |
| unequally | In an unequal manner. <botany> Unequally pinnate, pinnate, but with an odd number of leaflets. Source: Websters Dictionary (01 Mar 1998) |
| unequivocal | Not equivocal; not doubtful; not ambiguous; evident; sincere; plain; as, unequivocal evidence; unequivocal words. Unequiv"ocally, Unequiv"ocalness. Source: Websters Dictionary (01 Mar 1998) |
| unerupted tooth | A tooth prior to emergence; a tooth unable to break out or emerge from the dental alveolar tissues into the oral cavity. (05 Mar 2000) |