Avoid using whois on registrar sites to check availability. It's trivial for them to hijack that info and then allow someone else to see what domains people have been checking, so they can pre-emptively register them.
The best way is to check the TLD server directly, using "dig"
Failing that, use a real whois client (NOT anything web-based)
$ dig thisdomaindoesnotexist.com ns
; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> thisdomaindoesnotexist.com ns
com. 899 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1405884613 1800 900 604800 86400
$ whois thisdomaindoesnotexist.com
Whois Server Version 2.0
Domain names in the
with many different competing registrars. Go to http://www.internic.net/
for detailed information.
No match for "THISDOMAINDOESNOTEXIST.COM".
>>> Last update of whois database: Sun, 20 Jul 2014 19:30:55 UTC <<<