in brief

Also, in short; in a word. Concisely, in few words, to sum up. All three phrases usually precede or follow a summary statement, as in In brief, we didn't get much out of his speech, or There was no agenda; in short, they could discuss whatever they wanted to, or The sun was shining, the sky was clear--in a word, it was a beautiful day. The first expression dates from the early 1400s; in short dates from the 1300s but the present usage dates from the 1700s; the hyperbolic in a word (since there is nearly always more than one word) dates from the late 1500s.

Designation on a brief indicating the names of persons who contributed to the written product. Such persons may or may not be listed as the attorneys of record. Many reported cases list the attorneys of record and all persons "on the brief." See of counsel.

The adverb has one meaning:

Meaning #1: in a concise manner; in a few words
  Synonyms: concisely, briefly, shortly, in short