tercia

In Central America, 20^th century, a unit of length, literally, a “third.”

Costa Rica	27.866 centimeters (approximately 10.971 inches), a third of a vara. A synonym for the pie. [Costa Rica. Ministerio de formento.] Medidas y pesas del sistema m�trico, y tablas de equivalencia con las antiguas. San Jos� de Costa Rica: Imprenta nacional, 1885. United Nations, 1966.
El Salvador	= 1 foot, 30.48 centimeters, a third of a yard (UN, 1966)
Guatemala and Nicaragua	28.0 centimeters (approximately 11 inches), a third of a vara. (UN, 1966)
Mexico	279.333 millimeters, a third of a vara. Galv�n Riviera, 1844. Excerpt in Spanish with English translation.