apt-cache
To search for available packages, run
apt-cache search PKG_NAME
Example
boby@sok-01:~$ apt-cache search wget devscripts - scripts to make the life of a Debian Package maintainer easier wget - retrieves files from the web abcde - A Better CD Encoder apt-mirror - APT sources mirroring tool axel - light command line download accelerator filetea - Web-based file sharing system getdata - management of external databases libcupt4-2-downloadmethod-wget - flexible package manager -- wget download method libwget0 - Download library for files and recursive websites ow-shell - shell utilities to talk to an 1-Wire owserver puf - Parallel URL fetcher pwget - downloader utility which resembles wget (implemented in Perl) python-wget - pure Python download utility for Python 2 python3-wget - pure Python download utility for Python 3 snarf - command-line URL grabber tcllib - Standard Tcl Library texlive-latex-extra - TeX Live: LaTeX additional packages wget2 - file and recursive website downloader wget2-dev - development file for libwget2 wput - tiny wget-like ftp-client for uploading files boby@sok-01:~$