Definition:

man-db: The on-line manual pager This package provides the man command, the primary way of examining the on-line help files (manual pages). Other utilities provided include the whatis and apropos commands for searching the manual page database, the manpath utility for determining the manual page search path, and the maintenance utilities mandb, catman and zsoelim. man-db uses the groff suite of programs to format and display the manual pages.

From Debian 3.0r0 APT

* Linux/Unix/Computing Glossary