The term Halakhah does not occur in the Bible; it is found only in tannaitic and amoraic literature and not even in other literary sources of the Second Temple period. In its form, Halakhah is an Aramaic noun and the verb (halak = “to walk” or “to go”) from which it is derived, serves in its various forms, to denote a person who observes the Lord’s Torah and fulfils its commandments. Thus, one “walks” not only in “the ways of the Lord” (Exodus 18:20), but also “in His statutes” (Leviticus 26:3), “in His judgments” (Ezekiel 37:24) and “in His Torah” (Exodus 16:4). Walking is parallel to observing. Just as one walks along known roads but the act of walking also lays new paths, so too, although one observes the commandments in established ways, the act of observance itself creates new forms.
The definition given by Nathan b. Jehiel of Rome, the 11th century author of the Talmudic dictionary, Arukh, which describes Halakhah as “something which came from ancient days and [will last] to the end [of time], or [alternatively] something according to which Israel goes,” accurately reflects the double meaning of the term: 1. A tradition followed throughout generations, and 2. A way accepted by the people as a whole. This definition also implies that the Halakhah is not explicit in the Bible and that, unlike the Biblical commandments, its source is not in direct revelation. The term, nevertheless, does carry the connotation of authority which is in no way inferior to that of the commandments of the Torah itself. Indeed, the parameters of the Biblical commandments – such as the place and time of their observance and who is obliged to perform them – are fixed by the Halakhah.

Ephraim E. Urbach, The Halakhah: Its Sources and Development, trans. Raphael Posner (Ramat Gan: Massada; Jerusalem: Yad la-Talmud, 1986), 2-3.