quaternion: Meaning and Definition of

qua•ter•ni•on

1. a group or set of four persons or things.
2. four gathered sheets folded in two for binding together.
1. 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,&hasp; jk = −kj = i, and ki = −ik = j.
2. 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.