High Quality Content by WIKIPEDIA articles! In abstract algebra, the split-quaternions or coquaternions are elements of an associative algebra introduced by James Cockle in 1849 under the latter name. They are also known as para-quaternions (particularly in recent literature on para-quaternionic geometry) or hyperbolic quaternions, although historically the latter term has a different meaning. Like the quaternions introduced by Hamilton in 1843, they form a four dimensional real vector space equipped with a multiplicative operation. Unlike the quaternion algebra, the split-quaternions contain zero divisors, nilpotent elements, and nontrivial idempotents.