- an expression of the form a + bi + cj + dk, where a, b, c, and d are real numbers; i2 = j2 = k2 = −1; and ij = −ji = k, jk = −kj = i, and ki = −ik = j.
- a quantity or operator expressed as the sum of a real number and three complex numbers, equivalent to the quotient of two vectors. The field of quaternions is not commutative under multiplication.
- quaternary ammonium compound,
- quaternary structure,
Origin of quaternion
Examples from the Web for quaternion
Four soldiers formed a quaternion; four quaternions therefore were sixteen men, who were especially appointed to guard Peter."Granny's Chapters"|Lady Mary Ross
The quaternion was a gathering of four sheets of vellum, each folded once; thus forming sixteen pages.Illuminated Manuscripts in Classical and Mediaeval Times|J. Henry Middleton
These last words are incorrect in fact, for οὐκ ἄνθρωπος does not appear in the first Quaternion, but is reserved for the second.Aristotle|George Grote
His days are thus described: from dawn to the third hour he copied rapidly, filling a (quaternion) each day.The Mediaeval Mind (Volume I of II)|Henry Osborn Taylor
William Hare, the second of our quaternion, was also a native of Ireland, having been born in the neighbourhood of Londonderry.The Court of Cacus|Alexander Leighton