Octahedron. A solid contained by eight equal sides, which are equilateral triangles.
Octastyle, R. (ὀκτά-στυλος). An octastyle portico is a portico having eight columns in front; octastyle pediment, a pediment supported by eight columns. The pediment of the Parthenon at Athens, from which the Elgin Marbles come, is an octastyle.
Octave. (1) In Music, the longest interval in the diatonic scale; as from do to do, or C to C. (2) Chr. Eight days, or the eighth day after a Church festival (the festival being included) kept as a repetition or prolongation of the festival. It is a Western custom unknown to the Eastern Church.
October. The eighth month of the old Roman year, but the tenth in the calendar of Numa, Julius Cæsar, &c. It was sacred to Mars, and a horse called the October equus was annually sacrificed to Mars.
Octofoil, Her. A double quatrefoil; the difference of a ninth son.
Octophoron or Octaphoron, Gr. and R. (ὀκτώφορον). A litter (lectica) borne by eight slaves.
Fig. 495. Ocularium in a helmet.
Ocularium, Med. Lat. The narrow slit or opening for the sight in a helmet. (See Fig. [495].)
Oculus, Chr. A round window of frequent occurrence in the tympanum of the pediment in Latin basilicas, and occasionally in certain churches of the 11th century.