In mathematics, a metasymplectic space, introduced by Freudenthal(1959) and Tits (1974, 10.13), is a Tits building of type F4 (a specific generalized incidence structure).
The four types of vertices are called points, lines, planes, and symplecta.
References
Freudenthal, Hans (1959), "Beziehungen der E7 und E8 zur Oktavenebene. VIII-IX.", Nederlandse Akademie van Wetenschappen. Proceedings. Series A. (in German), 62: 447–465