WHOWAS [<nicks> [<count> [server]]]
The nicknames, the maximum amount of results and the remote server. If no arguments are given, your own nickname will be used. If no remote server is given, the server you are connected to will be used.
Displays historical user information.
/WHOWAS /WHOWAS mike /WHOWAS bob 10 /WHOWAS sarah 5 ircsource.irssi.org