The first Hebrew word in the Ten Plagues mnemonic דצ״ך עד״ש באח״ב is Detzach.
The mnemonic, commonly transliterated “D’tzach, Adash, B’achav,” compresses the Hebrew initials of the ten plagues into three groups of three letters and one group of a single? Actually, each group represents three plagues: דצ״ך stands for blood, frogs, and lice; עד״ש for wild animals or flies, pestilence, and boils; and באח״ב for hail, locusts, darkness, and the death of the firstborn. The first group’s letters form “Detzach.”
It is recited during the Passover Seder after the Ten Plagues are listed. Many Haggadot connect the mnemonic with Rabbi Judah’s classification of the plagues. A common mix-up is treating “Detzach” as the name of a plague; it is instead a memory device made from Hebrew initials. Transliteration varies, including D’tzach, Detzach, and Dezakh, but the underlying Hebrew word is the same.