Definition of "quaternion" []

• A set of four persons or items. (noun)
• Mathematics Any number of the form a + bi + cj + dk where a, b, c, and d are real numbers, ij = k, i2 = j2 = -1, and ij = -ji. Under addition and multiplication, quaternions have all the properties of a field, except multiplication is not commutative. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Outside the quaternion were the dancing Pauppukkeewis, the Whirlwind, and the fierce and shifty hero, Monobozho, the North-West"
• "But we would maintain, nevertheless, that it is the identical book, and explain this variation in the description by the circumstance that the library having, in the space of nearly two centuries, been materially enriched, numerous works, consisting in many cases only of a single "quaternion," were inserted in the volumes already existing."
• "Go to the use of a better (higher group symmetry) modern electrodynamics model (such as quaternion electrodynamics, very close to Maxwell's original theory), and the operation of such asymmetric systems now is included (as it was and is in Maxwell's original 20 quaternion-like equations in 20 unknowns)."