quaternion
noun
qua·ter·ni·on kwə-ˈtər-nē-ən 
kwä-
1
: a set of four parts, things, or persons
2
: any of a set of numbers that comprise a four-dimensional vector space with a basis consisting of the real number 1 and three imaginary units i, j, k, that follow special rules of multiplication, and that are used especially in computer graphics, robotics, and animation to rotate objects in three dimensions
Example Sentences
Recent Examples on the Web John Graves, a lawyer friend of Hamilton’s, subsequently showed that pairs of quaternions make octonions: numbers that define coordinates in an abstract 8-D space. 
Quanta Magazine, 20 July 2018 Like the quaternions, octonion multiplication is not commutative. Quanta Magazine, 25 Oct. 2018 Proof surfaced in 1898 that the reals, complex numbers, quaternions and octonions are the only kinds of numbers that can be added, subtracted, multiplied and divided. Quanta Magazine, 20 July 2018
Quanta Magazine, 20 July 2018 Like the quaternions, octonion multiplication is not commutative. Quanta Magazine, 25 Oct. 2018 Proof surfaced in 1898 that the reals, complex numbers, quaternions and octonions are the only kinds of numbers that can be added, subtracted, multiplied and divided. Quanta Magazine, 20 July 2018 Word History
Etymology
Middle English quaternyoun, from Late Latin quaternion-, quaternio, from Latin quaterni four each, from quater four times; akin to Latin quattuor four — more at four
First Known Use
14th century, in the meaning defined at sense 1