sorry for the basic question.
I want to remove the underscore as a delimiter. in other words
characters concatanate with underscore will be define as single word.

tomer walla.co.il> wrote:

You'll need to use (modify-syntax-entry ?_ "w") in the mode hook.

regards,
Nikolaj Schumacher

On Sep 16, 8:42 am, tomer walla.co.il> wrote:

This is done by modifying the syntax table. The syntax table depends
on the editing mode. Putting the following line in your .emacs will
treat the underscore as a word constituent in text-mode.

(modify-syntax-entry ?_ "w" text-mode-syntax-table)

You may want to have a look at the emacs wiki:
http://www.emacswiki.org/cgi-bin/wiki/EmacsSyntaxTable