This is the famous prayer recited on the Jewish New Year near some water source into which we cast all our sins. Based on Micah 7:19: “You will hurl (ve-tashlich) all their sins into the depths of the sea.”
The root sh-l-k(h) is less known than its closely related prolific sh-l-H (with Het) “to send (away), dismiss, free (slaves), expel, divorce; strip bare, flay, slough (Aramaic),” and probably to sh-l-y / n-sh-l “draw out” (Exodus 3:5); shilyah “placenta.”
Other words from sh-l-kh are shallekhet “falling (of leaves),” which seems like a metaphor for falling sins as well.
In the Judeo-Arabic of Iraq, like Yiddish and Ladino, there were loanwords from Hebrew, including ishlikhu bi-nTilah “Discard it at Ntilah (hand washing) ritual,” Don’t let it (an insult, etc.) upset you!
Yona Sabar is a professor of Hebrew and Aramaic in the department of Near Eastern Languages & Cultures at UCLA.