The word quaternion was coined by the Irish physicistastronomermathematician William Rowan Hamilton (17881856), and is a generalised complex number consisting of four components.
a + bi + cj + dk
Where a,b,c and d are Real numbers and
ij = ji = k; jk = kj = i; ki = ik = j
and i² = j² = k² = ijk = 1
