Mare Undarum

[ uhn-dahr-uh m ]
/ ʌnˈdɑr əm /

noun

(Sea of Waves) a dark plain in the first quadrant of the face of the moon: about 4800 sq. mi. (12,000 sq. km).
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019