Sinus Sabaeus

[ see-nuh s sa-bee-uh s, sahy- ]
/ ˈsi nəs sæˈbi əs, ˈsaɪ- /

noun

an area in the southern hemisphere and near the equator of Mars, appearing dark when viewed telescopically from the earth.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019