loez and laaz

One of the most familiar verses in Hallel is the opening of Tehillim 114:בְּצֵאת יִשְׂרָאֵל מִמִּצְרָיִם בֵּית יַעֲקֹב מֵעַם לֹעֵזA common translation is, “When Yisrael went forth from Egypt, the house of Yaakov from a people of foreign speech” (Tehillim 114:1). Yet לֹעֵז (loez), usually understood as describing someone who speaks a foreign or unintelligible language, appears only once in the Tanakh. The verse doesn't explicitly mention language. It only describes the Egyptians as an עַם לֹעֵז. How can we know what the word originally meant, and why did the psalmist use it to describe Egypt?The familiar interpretation is supported by later Hebrew. The Mishnah (Megillah 2:1) says:אֲבָל קוֹרִין אוֹתָהּ לַלּוֹעֲזוֹת בְּלַעַז“But it may be read for foreign-language speakers in a foreign language.” Here לועזות describes the speakers, while לעז denotes their language. Rashi later used בלעז to introduce translations into Old French. Still, a word's meaning can change over time, and this…