Ortive adjective [ Latin ortivus , from oriri , ortus , to rise: confer French ortive .] Of or relating to the time or act of rising; eastern; as, the ortive amplitude of a planet.

Ortolan noun [ French, from Italian ortolano ortolan, gardener, from Latin hortulanus gardener, from hortulus , dim. of hortus garden. So called because it frequents the hedges of gardens. See Yard an inclosure, and confer Hortulan .] (Zoology) (a) A European singing bird ( Emberiza hortulana ), about the size of the lark, with black wings. It is esteemed delicious food when fattened. Called also bunting . (b) In England, the wheatear ( Saxicola œnanthe ). (c) In America, the sora, or Carolina rail ( Porzana Carolina ). See Sora .

Ortygan noun [ Greek ..., ..., a quail.] (Zoology) One of several species of East Indian birds of the genera Ortygis and Hemipodius . They resemble quails, but lack the hind toe. See Turnix .

Orval noun [ French orvale .] (Botany) A kind of sage ( Salvia Horminum ).

Orvet noun [ French] (Zoology) The blindworm.

Orvietan noun [ French orviétan : confer Italian orvietano . So called because invented at Orvieto , in Italy.] A kind of antidote for poisons; a counter poison formerly in vogue. [ Obsolete]

Oryal, Oryall noun See Oriel .

Oryctere noun [ Greek ... digger: confer French oryctère .] (Zoology) The aard- vark.

Orycterope noun [ Greek ... digger + ... foot.] (Zoology) Same as Oryctere .

Oryctognosy noun [ Greek ... dug (... to dig) + ... knowledge.] Mineralogy. [ Obsolete] -- Or`yc*tog*nos"tic adjective -- Or`yc*tog*nos"tic*al adjective [ Obsolete] -- Or`yc*tog*nos"tic*al*ly adverb [ Obsolete]

Oryctography noun [ Greek ... dug + -graphy .] Description of fossils. [ Obsolete]

Oryctological adjective [ Confer French oryctologique .] Of or pertaining to oryctology. [ Obsolete]

Oryctologist noun One versed in oryctology. [ Obsolete]

Oryctology noun [ Greek ... dug + -logy : confer French oryctologie .]
1. An old name for paleontology.

2. An old name for mineralogy and geology.

Oryx noun [ New Latin , from Greek ... a kind of gazelle or antelope.] (Zoology) A genus of African antelopes which includes the gemsbok, the leucoryx, the bisa antelope ( O. beisa ), and the beatrix antelope ( O. beatrix ) of Arabia.

Oryza noun [ Latin , rice, Greek ... See Rice .] (Botany) A genus of grasses including the rice plant; rice.

Os noun ; plural Ossa . [ Latin ] A bone.

Os noun ; plural Osar . [ Swedish ås ridge, chain of hills, plural åsar .] (Geol.) One of the ridges of sand or gravel found in Sweden, etc., supposed by some to be of marine origin, but probably formed by subglacial waters. The osar are similar to the kames of Scotland and the eschars of Ireland. See Eschar .

Osage orange (Botany) An ornamental tree of the genus Maclura ( M. aurantiaca ), closely allied to the mulberry ( Morus ); also, its fruit. The tree was first found in the country of the Osage Indians, and bears a hard and inedible fruit of an orangelike appearance. See Bois d'arc .

Osages noun plural ; sing. Osage (Ethnol.) A tribe of southern Sioux Indians, now living in the Indian Territory.

Osanne noun Hosanna. [ Obsolete] Chaucer.

Osar noun plural (Geol.) See 3d Os .

Oscan adjective Of or pertaining to the Osci, a primitive people of Campania, a province of ancient Italy. -- noun The language of the Osci.

Oscillancy noun The state of oscillating; a seesaw kind of motion. [ R.]

Oscillaria noun [ New Latin , from Latin oscillare to swing.] (Botany) A genus of dark green, or purplish black, filamentous, fresh-water algæ, the threads of which have an automatic swaying or crawling motion. Called also Oscillatoria .

Oscillate intransitive verb [ imperfect & past participle Oscillated ; present participle & verbal noun Oscillating .] [ Latin oscillare to swing, from oscillum a swing, a little mask or puppet made to be hung from trees and swing in the wind, probably orig., a little mouth, a dim. from os mouth. See Oral , and confer Osculate .]

1. To move backward and forward; to vibrate like a pendulum; to swing; to sway.

2. To vary or fluctuate between fixed limits; to act or move in a fickle or fluctuating manner; to change repeatedly, back and forth.

The amount of superior families oscillates rather than changes, that is, it fluctuates within fixed limits.

Dc Quincey.

Oscillating adjective That oscillates; vibrating; swinging.

Oscillating engine , a steam engine whose cylinder oscillates on trunnions instead of being permanently fixed in a perpendicular or other direction. Weale.

Oscillating current (Electricity) A current alternating in direction.

Oscillation noun [ Latin oscillatio a swinging.]

1. The act of oscillating; a swinging or moving backward and forward, like a pendulum; vibration.

2. Fluctuation; variation; change back and forth.

His mind oscillated, undoubtedly; but the extreme points of the oscillation were not very remote.

Macaulay.

Axis of oscillation , Center of oscillation . See under Axis , and Center .

Oscillative adjective Tending to oscillate; vibratory. [ R.] I. Taylor.

Oscillator noun One that oscillates ; specif.: (a) (Electricity) Any device for producing electric oscillations; esp., an apparatus for generating electric waves in a system of wireless telegraphy. (b) (Mech.) An instrument for measuring rigidity by the torsional oscillations of a weighted wire.

Oscillatoria noun plural [ New Latin See Oscillatory .] (Botany) Same as Oscillaria .

Oscillatory adjective [ Confer French oscillatoire . See Oscillate .] Moving, or characterized by motion, backward and forward like a pendulum; swinging; oscillating; vibratory; as, oscillatory motion.

Oscillogram noun [ Latin oscillare + -gram .] (Electricity) An autographic record made by an oscillograph.

Oscillograph noun [ Latin oscillare to swing + -graph .] (Electricity) An apparatus for recording or indicating alternating-current wave forms or other electrical oscillations, usually consisting of a galvanometer with strong field, in which the mass of the moving part is very small and frequency of vibration very high. -- Os`cil*lo*graph"ic adjective

Oscillometer noun [ Latin oscillare to swing + -meter .] An instrument for measuring the angle through which a ship rolls or pitches at sea.

Oscilloscope noun [ Latin oscillare to swing + -scope .] (Electricity) An instrument for showing visually the changes in a varying current; an oscillograph.

Oscine adjective (Zoology) Relating to the Oscines.

Oscines noun plural [ Latin oscen , -inis .] (Zoology) Singing birds; a group of the Passeres, having numerous syringeal muscles, conferring musical ability.

Oscinian noun (Zoology) One of the Oscines, or singing birds.

Oscinine adjective (Zoology) Of or pertaining to the Oscines.

Oscitancy noun [ See Oscitant .]

1. The act of gaping or yawning.

2. Drowsiness; dullness; sluggishness. Hallam.

It might proceed from the oscitancy of transcribers.

Addison.

Oscitant adjective [ Latin oscitans , -antis , present participle of oscitare : confer French oscitant .]
1. Yawning; gaping.

2. Sleepy; drowsy; dull; sluggish; careless.

He must not be oscitant , but intent on his charge.

Barrow.

Oscitantly adverb In an oscitant manner.

Oscitate intransitive verb [ Latin oscitare ; os the mouth + citare , v. intens. from ciere to move.] To gape; to yawn.

Oscitation noun [ Latin oscitatio : confer French oscitation .] The act of yawning or gaping. Addison.

Osculant adjective [ Latin osculans , -antis , present participle of osculari to kiss. See Osculate .]

1. Kissing; hence, meeting; clinging.

2. (Zoology) Adhering closely; embracing; -- applied to certain creeping animals, as caterpillars.

3. (Biol.) Intermediate in character, or on the border, between two genera, groups, families, etc., of animals or plants, and partaking somewhat of the characters of each, thus forming a connecting link; interosculant; as, the genera by which two families approximate are called osculant genera.