The Collaborative International Dictionary of English v.0.48:

Octave \Oc"tave\, a.
   Consisting of eight; eight. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Octave \Oc"tave\, 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]

   Note: 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]

WordNet (r) 3.0 (2006):

octave
    n 1: a feast day and the seven days following it
    2: a musical interval of eight tones [syn: octave, musical
       octave]
    3: a rhythmic group of eight lines of verse

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "octave":
   English horn, Octateuch, Spenserian stanza, antistrophe, bassoon,
   block flute, bombard, book, bourdon, burden, canto, cello, chorus,
   claribel, clarinet, clarion, concert flute, consecutive intervals,
   contraoctave, cornet, cornopean, couplet, cromorna, cymbel, degree,
   diapason, diatessaron, diatonic interval, diatonic semitone,
   distich, double contraoctave, dulciana, eight,
   eighter from Decatur, eighth, enharmonic diesis,
   enharmonic interval, envoi, epode, fifth, flute stop,
   foundation stop, four-foot octave, four-line octave, fourniture,
   fourth, gamba, gedeckt, gemshorn, great octave, half step,
   halftone, harmonic flute, heptastich, hexastich, hybrid stop,
   interval, koppel flute, larigot, less semitone, line, measure,
   melodia, melodic interval, mixture, monostich, mutation stop,
   nazard, note, oboe, octad, octagon, octahedron, octameter,
   octastich, octastyle, octavo, octet, octonary, octosyllable,
   ogdoad, one-line octave, organ stop, ottava, ottava alta,
   ottava bassa, ottava rima, parallel octaves, pentastich, piccolo,
   plein jeu, posaune, principal, quatrain, quint, quintaten, rank,
   ranket, reed stop, refrain, register, rhyme royal, rohr flute,
   second, semitone, septet, sesquialtera, sestet, seventh, sextet,
   shawm, sixth, small octave, spitz flute, stanza, stave, step, stop,
   stopped diapason, stopped flute, strain, string diapason,
   string stop, strophe, subcontraoctave, syllable, tercet,
   terza rima, tetrastich, third, tierce, tone, tone row, tremolo,
   triplet, tristich, trombone, trumpet, twelfth, two-foot octave,
   two-line octave, unda maris, unison interval, utas, verse, vibrato,
   viola, voix celeste, vox angelica, vox humana, whole step



The Free On-line Dictionary of Computing (30 December 2018):

Octave

    A high-level interactive language by John
   W. Eaton, with help from many others, like MATLAB, primarily
   intended for numerical computations.  Octave provides a
   convenient command line interface for solving linear and
   nonlinear problems numerically.

   Octave can do arithmetic for real and complex scalars
   and matrices, solve sets of nonlinear algebraic equations,
   integrate functions over finite and infinite intervals, and
   integrate systems of ordinary differential and
   differential-algebraic equations.

   Octave has been compiled and tested with g++ and libg++ on a
   SPARCstation 2 running SunOS 4.1.2, an IBM RS/6000
   running AIX 3.2.5, DEC Alpha systems running OSF/1 1.3
   and 3.0, a DECstation 5000/240 running Ultrix 4.2a, and
   Intel 486 systems running Linux.  It should work on most
   other Unix systems with g++ and libg++.

   Octave is distributed under the GNU General Public
   License.  It requires gnuplot, a C++ compiler and
   Fortran compiler or f2c translator.

   home (http://che.wisc.edu/octave).

   (ftp://ftp.che.wisc.edu/pub/octave/) or your nearest GNU
   archive site.

   E-mail: .

   (2000-06-27)