The study of the properties of geometric figures that remain invariant under certain transformations, as bending or stretching. A circle is topologically equivalent to an ellipse (into which it can be deformed by stretching) and a sphere is equivalent to an ellipsoid.
From topo- combining form of Gk. topos "place" + → -logy.
Topošenâsi, from topo-, loan from Gk., as above, + šenâsi→ -logy.
A light to be carried in the hand, consisting of some combustible substance, as resinous wood, or of twisted flax or the like soaked with tallow or other flammable substance, ignited at the upper end (Dictionary.com).
M.E. torche, from O.Fr. torche "torch," originally "twisted thing," then "torch formed of twisted tow dipped in wax," probably from V.L. *torca, alteration of L.L. torqua, from torquere "to twist," → torque.
Âhir, from Kurd. âhir "torch," variant of âzar, → fire.
Fr.: échelle de Turin
A scale used to assess the threat posed by the → impact of a → near-Earth object (NEO). It considers the impact energy as well as the probability of impact. It is designed to communicate to the public the risk associated with a NEO in more qualitative form than the → Palermo scale. The → impact hazard is expressed by a number between 0 and 10 depending on the probability that an impact will occur and the kinetic energy of the potential → impactor. The extent of damage ranges from inconsequential (0) to catastrophic (10). The scale is color-coded such that white = no consequence; green = meriting careful monitoring; yellow = meriting concern; orange = threatening events; red = impact is certain.
Named for Torino, because the scale was adopted by that city in Italy in 1999; → scale.
pic-tuf, tufân-e picandé
A mass of rotating air with high wind speeds at its center. It is produced in a very severe thunderstorm and appears as a funnel cloud extending from the base of a Cumulonimbus to the ground.
Tornado, metathesis from Sp tronada "thunderstorm," from tronar "to thunder," from L. tonare "to thunder," → thunder.
Pic-tuf, from pic present stem of picidan
"to twist, entwine, coil" (Mid.Pers. pecidan "to twist, entwine") +
tuf short for tufân, → storm.
A surface of revolution obtained by rotating a closed plane curve about an axis parallel to the plane which does not intersect the curve. The simplest toroid is the → torus. The solid enclosed by such a surface.
toroidal magnetic field
meydân-e meqnâtisi-ye cambarvâr
Fr.: champ magnétique toroïdal
A magnetic field which is generated in a → plasma inside a → toroid, as in a → tokamak, by the electric current which spirals around the toroid. Toroidal field has no radial component. → poloidal magnetic field.
The tendency of a force applied to an object to cause the object to rotate about a given axis or point. Torque is a vector quantity. It is equal to the product of the force and its distance from the reference axis. Same as → moment.
From L. torquere "to twist;" cf. Skt. tarku- "spindle;" maybe Mod.Pers. duk "spindle;" Mid.Pers. dôk "spindle;" O.C.S. traku "band, girdle," O.H.G. drahsil "turner," Ger. drechseln "to turn on a lathe;" O.E. thweorh "transverse, perverse, angry, cross;" E. thwart; PIE base *twork-/*twerk- "twist"
Gaštâvar literally "that which makes turn, turning agent," from gašt "turning," past stem of gaštan, gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend") + âvar agent noun of âvardan "to bring; to cause, produce" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").
A unit of pressure used in the field of high vacuum, equivalent to 1 mm of mercury
After the Italian scientist Evangelista Torricelli (1608-1647), who invented the first barometer.
A stream of water flowing with great rapidity and violence. See also → rapids.
M.E., from M.Fr. torrent, from L. torrentem (nominative torrens) "a rushing (stream)," from torrere, "to parch, dry up, roast," → torrid.
Lâhez, from Tabari lahez "an overwhelming flow," Baxtiyâri lâhiz "flood." The first component lâh, lah maybe related to lur, Lori, Kordi laf, Tabari lé "flood," → cataclysm.
Fr.: loi de Torricelli
In fluid dynamics, a theorem that relates the speed of fluid flowing out of an opening to the height of fluid above the opening: v = (2gh)1/2, where v is the exit velocity of the water, h is the height of the water column, and g is the acceleration due to gravity (9.81 m/s2). It was later shown to be a particular case of → Bernoulli's theorem.
After the Italian scientist Evangelista Torricelli (1608-1647), who found this relationship in 1643.
Subject to the weather that is hot and dry enough to scorch land.
From L. torridus "dried with heat, scorching hot," from torrere "to dry up, roast," related to terra "earth," literally "dry land;" from PIE base *ters- "to dry" (cf. Pers. tešné "thirsty;" Mid.Pers. tašnak "thirsty;" Av. taršu- "dry," taršna- "thirst;" Skt. trsta- "dry," tars- "to be thirsty;" Gk. teresesthai "to become or be dry;" Goth. þaursus "dry, barren," O.H.G. derren "to make dry," durst "thirst;" Ger. dürr "arid;" O.E. þurstig "thirsty").
Tafsân, tafsâ, from tafsidan "to become hot," variants tâftan, tâbidan "to shine;" Mid.Pers. tâftan "to heat, burn, shine;" taftan "to become hot;" Parthian t'b "to shine;" Av. tāp-, taf- "to warm up, heat," tafsat "became hot," tāpaiieiti "to create warmth;" cf. Skt. tap- "; to heat, be/become hot; to spoil, injure, damage; to suffer," tapati "burns;" L. tepere "to be warm," tepidus "warm;" PIE base *tep- "to be warm."
Fr.: Zone torride
The part of the Earth's surface between the tropics of Cancer and Capricorn
A surface produced by the revolution of a conic section (such as a circle) around a line lying in its plane, but not cutting the conic. The solid enclosed by such a surface.
From L. torus "a round, swelling protuberance."
Cambar "torus," originally "hoop, circle," from Mid.Pers. cambar "hoop; a ring-shaped headdress," cambar vâcik "playing tambourine."
Constituting or comprising the whole; entire; complete in extent or degree.
Related term → general = harvin (
M.E., from O.Fr. total, from M.L. totalis "entire, total," from L. totus "all, whole, entire," of unknown origin.
Mid.Pers. hamâk, hamâg "total, all," hamâkih "totality," related to Mod.Pers. hamé- "all," variant hami "all the time, always;" Mid.Pers. hamê "all the time, always;" Av. hama- "any" (cf. Skt. sama-"any, every, whichever;" Gk. amo-then "whichever;" Goth. sums "any;" O.N. sumr "any;" O.E. sum "some;" E. some) + suffix -âk.
Fr.: abondance totale
Same as → elemental abundance.
Fr.: éclipse totale
Fr.: énergie totale
The sum of all forms of energy involved in a system.
Fr.: fonction totale
A function whose value is defined for all possible input values.
Fr.: gravité totale
total internal reflection
bâztâb-e hamâk-e daruni
Fr.: réflexion totale interne
A phenomenon occurring when a light ray traveling cross an → interface from a higher → refractive index medium to a lower refractive index medium hits the interface at an angle larger than the → critical angle. In these conditions the light will not pass through to the second → medium at all. Instead, all of it will be reflected back into the first medium.