The Definition(s) of Halacha

"In time, the term [halacha] came to denote several things:

1) 'a halakha', a law, the smallest unit of a halakhic collection, such as 'a halakha' from the Tosefta--involving the plural 'halakhot';

2) 'the halakha' as the accepted law, where different opinions exist, such as in the usage, 'A says....B says, but the halakha is...';

3) halakha (or 'halakhot') as an object of study and a literary genre, as opposed to aggada (aggadot);

4) 'the Halakha' as the legal aspect of Jewish life and the legal tradition of Judaism, in which one can distinguish, for example, between the halakha of the Sages and the halakha of Qumran,"  (from The Literature of the Sages Part 1, pg 121)