Well... Let's make this more complex based on the awk comment earlier...
cat * | awk '! a[$0]++' > NewFileName
cat * | ruby -ne 'puts $_ unless $_ == @prev; @prev = $_'
Here is some more fun (and why one should learn as many commands for as many systems as possible) ... Assuming you needed to get data out of a server but didn't have appropriate perms to xfer files or perhaps some minor hiccup like a firewall, NAC or DLP system just angered you. Assume the system had python...
So lets say these wordfiles were usernames you needed to access... You have 10 userlists you needed to handle... You were too lazy to copy them via term or something (terms are your friend... forget data extraction. Exfiltration = detection
Using nothing but system commands to feed them to your self with cat + awk + python
cat wordlists* | awk '! a[$0]++' > /tmp/YOURDIRNAMEHERE && cd /tmp
python -m SimpleHTTPServer 8000
"It pays to discover"