Issues with using sed with word delimiters \< and \>

sed is not applying /d "delete line" option when I also include match word options \< and \>

examples...
echo cat | sed '/\<cat\>/d'

will return cat for some reason

echo cat | sed "/\<cat\>/d"

will also still return cat.

Of course I can just run this... echo cat | sed '/cat/d' and it will apply delete option to line thus returning nothing.

But I need to match the word exactly.... so any advise of how to get around this?
I'm running on AIX. Same results with with ksh or bash shell.

No double posting!

Continue diskussion here.