Exodus 15:23

The waters of Marah... were bitter. — The extreme bitterness of the springs at the southern extremity of the wilderness of Shur is witnessed to by all travellers. (Burckhardt: Travels in Syria, p. 777; Robinson: Palestine, vol. i., p. 106; Wellsted, Arabia, vol. ii., p. 38, &c.) There are several such springs, that called Ain Howarah being the most copious, but scarcely so bitter as some others.

Therefore the name of it was called Marah. — “Marah” means “bitterness” both in Hebrew and in Arabic. It appears to be a form of the root which we find also in mare and amarus.