‖n. pl. [ NL., fr. Gr. 'a priv. + prwkto`s anus. ] (Zool.) A group of Turbellaria in which there is no anal aperture. [ 1913 Webster ]

n. pl.; sing. Choctaw. (Ethnol.) A tribe of North American Indians (Southern Appalachian), in early times noted for their pursuit of agriculture, and for living at peace with the white settlers. They are now one of the civilized tribes of the Indian Territory. [ 1913 Webster ]

a. Presenting a combination of a cube and an octahedron. [ 1913 Webster ]

n. (Crystallog.) A combination of a cube and octahedron, esp. one in which the octahedral faces meet at the middle of the cubic edges. [ 1913 Webster ]

‖n. pl. [ NL., fr. Gr. 'ekto`s outside outside + &unr_; the anus. ] (Zoöl.) An order of Bryozoa in which the anus lies outside the circle of tentacles. [ 1913 Webster ]

‖n. pl. [ NL., fr. Gr. &unr_; within + &unr_; the anus. ] (Zoöl.) A group of Bryozoa in which the anus is within the circle of tentacles. See Pedicellina. [ 1913 Webster ]

n. [ Hex- + octahedron. ] (Geom.) A solid having forty-eight equal triangular faces. [ 1913 Webster ]

n. [ L. nox, noctis, night + ambulare to walk: cf. F. noctambulation. ] Somnambulism; sleepwalking; walking in one's sleep. Quain. [ 1913 Webster +PJC ]

n. Somnambulism.
Syn. -- sleepwalking; noctambulation. [ 1913 Webster ]

n. A somnambulist; a sleepwalker. [ 1913 Webster ]

n. A noctambulist; a sleepwalker. [ Obs. ] [ 1913 Webster ]

A prefix meaning eight. See Octo-. [ 1913 Webster ]

{ . [ L. octo eight, Gr. 'oktw`, with a combining form 'okta-. Cf. Eight. ] A combining form meaning eight; as in octodecimal, octolocular. [ 1913 Webster ]

n. [ Gr. &unr_; with eight strings; 'okta- (for 'oktw` eight) + &unr_; string, chord: cf. F. octacorde. ] (Mus.) An instrument of eight strings; a system of eight tones. [ Also written octochord. ] [ 1913 Webster ]

n. [ Gr. &unr_;, &unr_;, the number eight. ] 1. (Chem.) An atom or radical which has a valence of eight, or is octavalent. [ 1913 Webster ]

2. A group of eight things. [ PJC ]

a. See Octahedral. [ 1913 Webster ]

‖n. [ NL., fr. Gr. &unr_;, neut. of &unr_; of the eighth day. ] (Eccl.) A fast of eight days before a great festival. Shipley. [ 1913 Webster ]

n. [ Gr. &unr_; eight-cornered; 'okta- (for 'oktw` eight) + &unr_; an angle: cf. F. cctogone. ] 1. (Geom.) A plane figure of eight sides and eight angles. [ 1913 Webster ]

2. Any structure (as a fortification) or place with eight sides or angles. [ 1913 Webster ]

Regular octagon, one in which the sides are all equal, and the angles also are all equal. [ 1913 Webster ]

a. Having eight sides and eight angles. [ 1913 Webster ]

a. [ Octa- + Gr. gynh` wife. ] (Bot.) Having eight pistils or styles; octogynous. [ 1913 Webster ]

a. [ See octahedron. ] Having eight faces or sides; of, pertaining to, or formed in, octahedrons; as, octahedral cleavage; an octahedral crystal. [ 1913 Webster ]

octahedral borax (Chem.), borax obtained from a saturated solution in octahedral crystals, which contain five molecules of water of crystallization; distinguished from common or prismatic borax. --
Octahedral iron ore (Min.), magnetite. [ 1913 Webster ]

n. (Min.) Titanium dioxide occurring in acute octahedral crystals. [ 1913 Webster ]

n. [ Gr. 'okta`edron, fr. 'okta`edros eight-sided; 'okta- (for 'oktw` eight) + "e`dra seat, base, from "e`zesqai to sit. ] (Geom.) A solid bounded by eight faces. The regular octahedron is contained by eight equal equilateral triangles. [ 1913 Webster ]

n. [ Octa- + Gr. me`ros part. ] (Chem.) A molecule composed of eight monomer units bound to each other, usually in a linear array; as, an octamer formed from eight nucleotides is called an octanucleotide. [ PJC ]

An example of an octapeptide might be represented using the standard abbreviations for the component amino acids, e.g.: met-ala-ser-glu-lys-ala-val-gly

An octanucleotide might be represented using the standard single-letter abbreviations for the component mononucleotides, e.g.: ATGCATGC. [ PJC ]

a. [ Octa- + Gr. me`ros part. ] (Biol.) Having the parts in eights; as, an octamerous flower; octamerous mesenteries in polyps. [ 1913 Webster ]

n. [ Cf.L. octameter in eight feet. See Octa-, and meter. ] (Pros.) A verse containing eight feet; as, --

Deep&bprime_; in|to&bprime_; the | dark&bprime_;ness | peer&bprime_;ing, | long&bprime_; I | stood&bprime_; there | wond'&bprime_;ring, | fear&bprime_;ing. Poe. [ 1913 Webster ]

n. One of the Octandria. [ 1913 Webster ]

‖prop. n. pl. [ NL., fr. Gr. 'okta- (for 'oktw` eight) + &unr_;, &unr_;, male, man. ] (Bot.) A Linnaean class of plants, in which the flowers have eight stamens not united to one another or to the pistil. [ 1913 Webster ]

{ } a. (Bot.) Of or pertaining to the Octandria; having eight distinct stamens. [ 1913 Webster ]

n. [ See Octa- ] (Chem.) Any one of a group of metametric hydrocarbons (C8H18) of the methane (paraffin) series. The most important is a colorless, volatile, inflammable liquid, found in petroleum, and a constituent of gasoline or ligroin. [ 1913 Webster +PJC ]

a. [ L. octangulus eight-cornered; octo eight + angulus angle. ] Having eight angles; eight-angled. -- Oc*tan"gu*lar*ness, n. [1913 Webster]

n. [ L. octans, -antis. fr. octo eight. See Octave. ] 1. (Geom.) The eighth part of a circle; an arc of 45 degrees. [ 1913 Webster ]

2. (Astron. & Astrol.) The position or aspect of a heavenly body, as the moon or a planet, when half way between conjunction, or opposition, and quadrature, or distant from another body 45 degrees. [ 1913 Webster ]

3. An instrument for measuring angles (generally called a quadrant), having an arc which measures up to 9O°, but being itself the eighth part of a circle. Cf. Sextant. [ 1913 Webster ]

4. (Math. & Crystallog.) One of the eight parts into which a space is divided by three coordinate planes. [ 1913 Webster ]

n. [ Octa- + nucleotide. ] (Chem.) A molecule composed of eight nucleotide units bound to each other by phosphodiester bonds in a linear array; as, a partial digest of DNA or RNA may include octanucleotides. See octamer. [ PJC ]

n. [ Octa- + peptide. ] (Chem.) A molecule composed of eight amino acid units bound to each other by peptide bonds, usually in a linear array. See octamer. [ PJC ]

‖prop. n.; etymol. pl., but syntactically sing. [ NL., fr. Gr. 'okta- (for 'oktw` eight) + -pla, as in E. hexapla; cf. Gr. &unr_; eightfold. ] A portion of the Old Testament prepared by Origen in the 3d century, containing the Hebrew text and seven Greek versions of it, arranged in eight parallel columns. [ 1913 Webster ]

n. See Octoroon. [ 1913 Webster ]

a. See Octostyle. [ 1913 Webster ]

n. [ L. octateuchus, Gr. &unr_;. ] A collection of eight books; especially, the first eight books of the Old Testament. [ R. ] [ 1913 Webster ]

a. [ Octa- + L. valens, p. pr. See Valence. ] (Chem.) Having a valence of eight; capable of being combined with, exchanged for, or compared with, eight atoms of hydrogen; -- said of certain atoms or radicals. [ 1913 Webster ]

n. [ F., fr. L. octava an eighth, fr. octavus eighth, fr. octo eight. See Eight, and cf. Octavo, Utas. ] 1. The eighth day after a church festival, the festival day being included; also, the week following a church festival. “The octaves of Easter.” Jer. Taylor. [ 1913 Webster ]

2. (Mus.) (a) The eighth tone in the scale; the interval between one and eight of the scale, or any interval of equal length; an interval of five tones and two semitones. (b) The whole diatonic scale itself. [ 1913 Webster ]

☞ The ratio of a musical tone to its octave above is 1:2 as regards the number of vibrations producing the tones. [ 1913 Webster ]

3. (Poet.) The first two stanzas of a sonnet, consisting of four verses each; a stanza of eight lines. [ 1913 Webster ]

With mournful melody it continued this octave. Sir P. Sidney. [ 1913 Webster ]

Double octave. (Mus.) See under Double. --
Octave flute (Mus.), a small flute, the tones of which range an octave higher than those of the German or ordinary flute; -- called also piccolo. See Piccolo. [ 1913 Webster ]

4. A small cask of wine, the eighth part of a pipe. [ 1913 Webster ]

a. Consisting of eight; eight. Dryden. [ 1913 Webster ]

n.;pl. Octavos [ L. in octavo; in in + octavo, abl. of octavus. See Octave. ] A book composed of sheets each of which is folded into eight leaves; hence, indicating more or less definitely a size of book so made; -- usually written 8vo or 8°. [ 1913 Webster ]

a. Having eight leaves to a sheet; as, an octavo form, book, leaf, size, etc. [ 1913 Webster ]

n. One who watches or keeps awake all night. [ 1913 Webster ]

n. [ L. pernoctatio, fr. pernoctare to stay all night; per + nox, noctis, night. ] The act or state of passing the whole night; a remaining all night. “Pernoctation in prayer.” Jer. Taylor. [ 1913 Webster ]

{ } a. Containing one part of eight; having the ratio of one to eight. Bp. Wilkins. [ 1913 Webster ]

n. [ Gr. &unr_; thrice + E. octahedron. ] (Crystalloq.) A trigonal trisoctahedron. [ 1913 Webster ]

n. [ Gr. &unr_; thrice + FE. octahedron. ] (Crystallog.) A solid of the isometric system bounded by twenty-four equal faces, three corresponding to each face of an octahedron. [ 1913 Webster ]

Tetragonal trisoctahedron, a trisoctahedron each face of which is a quadrilateral; called also trapezohedron and icositetrahedron. --
Trigonal trisoctahedron, a trisoctahedron each face of which is an isosceles triangle. [ 1913 Webster ]