The Collaborative International Dictionary of English v.0.48:

Briefly \Brief"ly\ (br[=e]f"l[y^]), adv.
   Concisely; in few words.
   [1913 Webster]

WordNet (r) 3.0 (2006):

briefly
    adv 1: for a short time; "she visited him briefly"; "was briefly
           associated with IBM"
    2: in a concise manner; in a few words; "the history is summed
       up concisely in this book"; "she replied briefly"; "briefly,
       we have a problem"; "to put it shortly" [syn: concisely,
       briefly, shortly, in brief, in short]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "briefly":
   accurately, aphoristically, bluntly, brusquely, compendiously,
   concisely, crisply, curtly, economically, exactly, fleetingly,
   flickeringly, flittingly, for a moment, hastily, hurriedly,
   in a capsule, in a nutshell, in an instant, in brief,
   in brief compass, in short, laconically, momentarily, pithily,
   pointedly, precisely, quickly, sententiously, shortly, sparely,
   succinctly, summarily, swiftly, synoptically, tersely,
   transiently