| rat | 1. <zoology> One of the several species of small rodents of the genus Mus and allied genera, larger than mice, that infest houses, stores, and ships, especially the Norway, or brown, rat (M. Alexandrinus). These were introduced into Anerica from the Old World. 2. A round and tapering mass of hair, or similar material, used by women to support the puffs and rolls of their natural hair. 3. One who deserts his party or associates; hence, in the trades, one who works for lower wages than those prescribed by a trades union. "It so chanced that, not long after the accession of the house of Hanover, some of the brown, that is the German or Norway, rats, were first brought over to this country (in some timber as is said); and being much stronger than the black, or, till then, the common, rats, they in many places quite extirpated the latter. The word (both the noun and the verb to rat) was first, as we have seen, leveled at the converts to the government of George the First, but has by degrees obtained a wide meaning, and come to be applied to any sudden and mercenary change in politics." Bamboo rat, any American rat of the genus Neotoma, especially N. Floridana, common in the Southern United States. Its feet and belly are white. Origin: AS. Raet; akin to D. Rat, OHG. Rato, ratta, G. Ratte, ratze, OLG. Ratta, LG. & Dan. Rotte, Sw. Ratta, F. Rat, Ir. & Gael radan, Armor. Raz, of unknown origin. Cf. Raccoon. Source: Websters Dictionary (01 Mar 1998) |
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| rat leprosy | A slowly but progressively fatal form of leprosy occurring in rats, caused by Mycobacterium lepraemurium; it appears in two forms, glandular and musculocutaneous; causes induration, alopecia, and eventually ulceration. Synonym: mouse leprosy, murine leprosy. (05 Mar 2000) |
| rat mite dermatitis | An eruption of wheals, papules, or vesicles caused by the rat mite. (05 Mar 2000) |
| rat sialodacryoadenitis virus | A coronavirus causing sialodacryoadenitis in rats. (05 Mar 2000) |
| rat-bite disease | A syndrome characterised by recurring fever, rash, and arthralgias occurring days to weeks after a rat bite. The causative agents are either streptobacillus moniliformis or spirillum minus. (12 Dec 1998) |
| rat-bite fever | A syndrome characterised by recurring fever, rash, and arthralgias occurring days to weeks after a rat bite. The causative agents are either streptobacillus moniliformis or spirillum minus. (12 Dec 1998) |
| rat-flea typhus | Murine typhus, an acute infectious disease with fever, headache, and rash, all quite similar to, but milder than, epidemic typhus, caused by a related microoganism, rickettsia typhi (mooseri), transmitted to humans by rat fleas (xenopsylla cheopis). The animal reservoir includes rats, mice and other rodents. Murine typhus occurs sporadically worldwide but is more prevalent in congested rat-infested urban areas. Also known as endemic typhus and urban typhus of malaya. (12 Dec 1998) |
| rat-tail | 1. <veterinary> An excrescence growing from the pastern to the middle of the shank of a horse. 2. <zoology> The California chimaera. See Chimaera. Any fish of the genus Macrurus. See Grenadier. Source: Websters Dictionary (01 Mar 1998) |
| rat-tailed | <zoology> Having a long, tapering tail like that of a rat. <zoology> Rat-tailed larva, the musk shrew. Source: Websters Dictionary (01 Mar 1998) |
| rata | <botany> A New Zealand forest tree (Metrosideros robusta), also, its hard dark red wood, used by the Maoris for paddles and war clubs. Origin: Maori. Source: Websters Dictionary (01 Mar 1998) |
| ratafia | A spirituous liquor flavored with the kernels of cherries, apricots, peaches, or other fruit, spiced, and sweetened with sugar; a term applied to the liqueurs called noyau, curacao, etc. Alternative forms: ratifia and ratafee. Origin: F, fr. Malay arak arrack + tafia a spirit distilled from molasses. Source: Websters Dictionary (01 Mar 1998) |
| ratany | <botany> Same as Rhatany. Source: Websters Dictionary (01 Mar 1998) |
| ratch | <zoology> Same as Rotche. Source: Websters Dictionary (01 Mar 1998) |
| ratchet | 1. A pawl, click, or detent, for holding or propelling a ratchet wheel, or ratch, etc. 2. A mechanism composed of a ratchet wheel, or ratch, and pawl. See Ratchet wheel, below, and 2d Ratch. Ratchet brace, a circular wheel having teeth, usually angular, with which a reciprocating pawl engages to turn the wheel forward, or a stationary pawl to hold it from turning backward. In the cut, the moving pawl c slides over the teeth in one direction, but in returning, draws the wheel with it, while the pawl d prevents it from turning in the contrary direction. Origin: Properly a diminutive from the same word as rack: cf. F. Rochet. See Ratch, Rack the instrument. Source: Websters Dictionary (01 Mar 1998) |
| rate | The number of occurrences in one minute (for example respiratory rate, heart rate) (27 Sep 1997) |
| water rat | 1. <zoology> The water vole. See Vole. The muskrat. The beaver rat. See Beaver. 2. A thief on the water; a pirate. Source: Websters Dictionary (01 Mar 1998) |
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| coronavirus, rat | A species of coronavirus causing pneumonia in newborn rats but a clinically inapparent infection in adults. It is separate but antigenetically related to mouse hepatitis virus (gastroenteritis virus, murine). (12 Dec 1998) |
| sea rat | 1. A pirate. 2. <zoology> The chimaera. Source: Websters Dictionary (01 Mar 1998) |
| typhus, rat-flea | See Typhus, murine. (12 Dec 1998) |
| Kilham rat virus | A virus of the genus Parvovirus causing inapparent infection in rats; also recoverable from rat tumours. Synonym: latent rat virus. (05 Mar 2000) |
| latent rat virus | A virus of the genus Parvovirus causing inapparent infection in rats; also recoverable from rat tumours. Synonym: latent rat virus. (05 Mar 2000) |