ad. In a passable fashion, moderately; adequately.
the GNU version of the Collaborative International Dictionary of English
ad. Tolerably; moderately.
The Century Dictionary and Cyclopedia
Tolerably; moderately.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. to a moderately sufficient extent or degree
Word Usage
"Philip Glass was probably the last one whose name would be passably well known to the public at large, and even Mr. Glass isn't nearly as famous as, say, Aaron Copland."