| virtual focus | The point from which divergent rays seem to proceed, or that at which they would meet if prolonged backward. (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) |
| virtue | 1. Manly strength or courage; bravery; daring; spirit; valor. "Built too strong For force or virtue ever to expugn." (Chapman) 2. Active quality or power; capacity or power adequate to the production of a given effect; energy; strength; potency; efficacy; as, the virtue of a medicine. "Jesus, immediately knowing in himself that virtue had gone out of him, turned him about." (Mark v. 30) "A man was driven to depend for his security against misunderstanding, upon the pure virtue of his syntax." (De Quincey) "The virtue of his midnight agony." (Keble) 3. Energy or influence operating without contact of the material or sensible substance. "She moves the body which she doth possess, yet no part toucheth, but by virtue's touch." (Sir. J. Davies) 4. Excellence; value; merit; meritoriousness; worth. "I made virtue of necessity." (Chaucer) "In the Greek poets, . . . The economy of poems is better observed than in Terence, who thought the sole grace and virtue of their fable the sticking in of sentences." (B. Jonson) 5. Specifically, moral excellence; integrity of character; purity of soul; performance of duty. "Virtue only makes our bliss below." (Pope) "If there's Power above us, And that there is all nature cries aloud Through all her works, he must delight in virtue." (Addison) 6. A particular moral excellence; as, the virtue of temperance, of charity, etc. "The very virtue of compassion." . "Remember all his virtues." . 7. Specifically: Chastity; purity; especially, the chastity of women; virginity. "H. I believe the girl has virtue. M. And if she has, I should be the last man in the world to attempt to corrupt it." (Goldsmith) 8. One of the orders of the celestial hierarchy. "Thrones, dominations, princedoms, virtues, powers." (Milton) Cardinal virtues. See Cardinal, In, or By, virtue of, through the force of; by authority of. "He used to travel through Greece by virtue of this fable, which procured him reception in all the towns." . "This they shall attain, partly in virtue of the promise made by God, and partly in virtue of piety." . Theological virtues, the three virtues, faith, hope, and charity. See . Origin: OE. Vertu, F. Vertu, L. Virtus strength, courage, excellence, virtue, fr. Vir a man. See Virile, and cf. Virtu. Source: Websters Dictionary (01 Mar 1998) |
| virtuous | 1. Possessing or exhibiting virtue. Specifically: Exhibiting manly courage and strength; valorous; valiant; brave. "Old Priam's son, amongst them all, was chiefly virtuous." (Chapman) Having power or efficacy; powerfully operative; efficacious; potent. "Lifting up his virtuous staff on high, He smote the sea, which calmed was with speed." (Spenser) "Every virtuous plant and healing herb." (Milton) Having moral excellence; characterised by morality; upright; righteous; pure; as, a virtuous action. "The virtuous mind that ever walks attended By a strong siding champion, conscience." (Milton) 2. Chaste; pure; applied especially to women. "Mistress Ford . . . The virtuous creature, that hath the jealous fool to her husband." (Shak) Vir"tuously, Vir"tuousness. Origin: OE. Vertuous, OF. Vertuos, vertuous, F. Vertueux, fr. L. Virtuous. See Virtue, and cf. Virtuoso. Source: Websters Dictionary (01 Mar 1998) |
| virucidal | Destructive to a virus. Synonym: viricidal. (05 Mar 2000) |
| virucide | <pharmacology> A chemical that destroys or inactivates a virus. (09 Oct 1997) |
| virucopria | Presence of virus in faeces. Origin: virus + G. Kopros, faeces (05 Mar 2000) |
| virulence | <microbiology> The degree or ability of a pathogenic organism to cause disease. (09 Oct 1997) |
| virulent | Extremely toxic, denoting a markedly pathogenic microorganism. Origin: L. Virulentus, poisonous (05 Mar 2000) |
| virulent bacteriophage | A bacteriophage that regularly causes lysis of the bacteria that it infects; it may exist in one or the other of only two forms, vegetative or mature; it does not have a probacteriophage form (i.e., its genome does not incorporate with that of the host bacterium), therefore it does not effect lysogenization. (05 Mar 2000) |
| virulent bubo | chancroidal bubo |
| virulent phage mutant | A mutant of a phage that is unable to establish lysogeny. (05 Mar 2000) |
| viruliferous | Conveying virus. (05 Mar 2000) |
| viruria | Presence of viruses in the urine. Origin: virus + G. Ouron, urine (05 Mar 2000) |
| virus | <virology> Viruses are obligate intracellular parasites of living but noncellular nature, consisting of DNA or RNA and a protein coat. They range in diameter from 20-300nm. Class I viruses (Baltimore classification) have double stranded DNA as their genome. Class II have a single stranded DNA genome. Class III have a double stranded RNA genome. Class IV have a positive single stranded RNA genome, the genome itself acting as mRNA. Class V have a negative single stranded RNA genome used as a template for mRNA synthesis. Class VI have a positive single stranded RNA genome but with a DNA intermediate not only in replication but also in mRNA synthesis. The majority of viruses are recognised by the diseases they cause in plants, animals and prokaryotes. Viruses of prokaryotes are known as bacteriophages. (13 Oct 1997) |