a traditional Hebrew unit of time equal to 1/1080 hour, 1/18 minute or 10/3 seconds. The plural is halakim. Halakim are used in formulas establishing the instant of new moon, which marks the start of the month in the Jewish calendar. In English, the unit is often called a part of an hour. The Jews inherited this unit from the Babylonians; it was widely used throughout the ancient Middle East.

The helek (Hebrew, meaning "portion", plural halakim) is a unit of time used in the calculation of the Hebrew calendar. The hour is divided into 1080 halakim. A helek is 31/3 seconds or 1/18 minute.