qua·ter·ni·on /kwəˈtɝniən, kwɑ-/
  四個一組,四人一組,四元數
  quaternion
  四元數
  Qua·ter·ni·on n.
  1. The number four. [Poetic]
  2. A set of four parts, things, or person; four things taken collectively; a group of four words, phrases, circumstances, facts, or the like.
     Delivered him to four quaternions of soldiers.   --Acts xii. 4.
  Ye elements, the eldest birth
   Of Nature's womb, that in quaternion run.   --Milton.
     The triads and quaternions with which he loaded his sentences.   -- Sir W. Scott.
  3. A word of four syllables; a quadrisyllable.
  4. Math. The quotient of two vectors, or of two directed right lines in space, considered as depending on four geometrical elements, and as expressible by an algebraic symbol of quadrinomial form.
  Note: ☞ The science or calculus of quaternions is a new mathematical method, in which the conception of a quaternion is unfolded and symbolically expressed, and is applied to various classes of algebraical, geometrical, and physical questions, so as to discover theorems, and to arrive at the solution of problems.
  Qua·ter·ni·on, v. t. To divide into quaternions, files, or companies.
  ◄ ►
  quaternion
       n : the cardinal number that is the sum of three and one [syn: four,
            4, IV, tetrad, quatern, quaternary, quaternity,
            quartet, quadruplet, foursome, Little Joe]
  Quaternion
     a band of four soldiers. Peter was committed by Herod to the
     custody of four quaternions, i.e., one quaternion for each watch
     of the night (Acts 12:4). Thus every precaution was taken
     against his escape from prison. Two of each quaternion were in
     turn stationed at the door (12:6), and to two the apostle was
     chained according to Roman custom.