Harm, and a Sound the Hebrew Alphabet Never Had a Sign For

Harm wrote a velar fricative in the classical language, the sound at the end of the Scottish pronunciation of loch. Its closest cognate in a living script is the Arabic kha. Hebrew and Syriac have no separate letter for it at all.

That absence is the point. Proto-Semitic is reconstructed with both a pharyngeal and a velar fricative, and in the Canaanite languages the two merged before the twenty-two letter alphabet was fixed. When Hebrew and the other Northwest Semitic scripts inherited that alphabet they inherited a signary that already had one letter where the parent had two, and nothing later in Hebrew can recover the distinction from the script itself. Arabic, whose alphabet was extended with dots to write consonants the borrowed Aramaic signary did not cover, has a separate kha. Ge'ez inherited a larger inventory directly from the South Arabian script, which had not merged them.

So a Ge'ez text and an Arabic text can distinguish two words that a Hebrew text writes identically, and the merger visible in the Northwest Semitic alphabet is datable to before that alphabet was fixed. The atlas relates harm to the Arabic kha as the cognate preserving the phoneme, and to the Hebrew cheth as the letter that absorbed it, with the merger stated on the relation rather than left to be inferred.