RegEx to find whole word, but not abbreviation - regex

Question

I am using RegEx in my .htaccess file to determine what URIs get sent to my router file. I have a problem though because one page that I need to route contains a string that I'm filtering out, causing that URI not to be sent to the router. I don't want the URIs with "adm" in them to be sent to the router, but this also means that it filters out URIs with strings like "admonish" or "administrate".
.htaccess:
<IfModule mod_rewrite.c>
Options +FollowSymlinks
# Options +SymLinksIfOwnerMatch
RewriteEngine On
RewriteBase /
RewriteCond %{HTTPS} off
#RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
</IfModule>
<IfModule mod_rewrite.c>
RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^http://%1%{REQUEST_URI} [R=301,L]
</IfModule>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule !(^adm|^ajax|^google([a-z0-9])|^tools|^swf|^confirm|^style) index.php [nc]
I've tried things like RewriteRule !(^adm(![in])|^ajax|^google([a-z0-9])|^tools|^swf|^confirm|^style) index.php [nc] and RewriteRule !(^adm(!in)|^ajax|^google([a-z0-9])|^tools|^swf|^confirm|^style) index.php [nc], but with no success.
What is the correct way to match a portion of a word if it is not followed by characters other than "/"?
EDIT - This is the current Rewrite as suggested:
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule !(^(?i)\badm(?=[a-z])|^ajax|^google([a-z0-9])|^tools|^swf|^confirm|^style) index.php [nc]
Still no luck with this, though.
UPDATE - Full .htaccess file:
DirectoryIndex index.php
<IfModule mod_rewrite.c>
Options +FollowSymlinks
# Options +SymLinksIfOwnerMatch
RewriteEngine On
RewriteBase /
RewriteCond %{HTTPS} off
#RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
</IfModule>
<IfModule mod_rewrite.c>
RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^http://%1%{REQUEST_URI} [R=301,L]
</IfModule>
RewriteCond %{REQUEST_URI} !/(adm|ajax|google([a-z0-9])|tools|swf|confirm|style) [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L]
# Rewrite requests for sitemap.xml
RewriteRule sitemap.xml$ sitemap.php?target=google [L]
# Rewrite requests for urllist.txt
RewriteRule urllist.txt$ sitemap.php?target=yahoo [L]
Options -MultiViews
# ----------------------------------------------------------------------
# Custom 404 page
# ----------------------------------------------------------------------
# You can add custom pages to handle 500 or 403 pretty easily, if you like.
# If you are hosting your site in subdirectory, adjust this accordingly
# e.g. ErrorDocument 404 /subdir/404.html
ErrorDocument 400 /error.php?e=400
ErrorDocument 401 /error.php?e=401
ErrorDocument 403 /error.php?e=403
ErrorDocument 404 /error.php?e=404
ErrorDocument 500 /error.php?e=500
# ----------------------------------------------------------------------
# UTF-8 encoding
# ----------------------------------------------------------------------
# Use UTF-8 encoding for anything served text/plain or text/html
AddDefaultCharset utf-8
# Force UTF-8 for a number of file formats
AddCharset utf-8 .atom .css .js .json .rss .vtt .xml
# ----------------------------------------------------------------------
# A little more security
# ----------------------------------------------------------------------
# To avoid displaying the exact version number of Apache being used, add the
# following to httpd.conf (it will not work in .htaccess):
# ServerTokens Prod
# "-Indexes" will have Apache block users from browsing folders without a
# default document Usually you should leave this activated, because you
# shouldn't allow everybody to surf through every folder on your server (which
# includes rather private places like CMS system folders).
<IfModule mod_autoindex.c>
Options -Indexes
</IfModule>
# Block access to "hidden" directories or files whose names begin with a
# period. This includes directories used by version control systems such as
# Subversion or Git.
<IfModule mod_rewrite.c>
RewriteCond %{SCRIPT_FILENAME} -d [OR]
RewriteCond %{SCRIPT_FILENAME} -f
RewriteRule "(^|/)\." - [F]
</IfModule>
# Block access to backup and source files. These files may be left by some
# text/html editors and pose a great security danger, when anyone can access
# them.
<FilesMatch "(\.(bak|config|sql|fla|psd|ini|log|sh|inc|swp|dist)|~)$">
Order allow,deny
Deny from all
Satisfy All
</FilesMatch>
# Increase cookie security
<IfModule php5_module>
php_value session.cookie_httponly true
php_value error_log /logs/php_errors.log
</IfModule>
# prevent access to PHP error log
<Files php_errors.log>
Order allow,deny
Deny from all
Satisfy All
</Files>
EDIT AGAIN:
I have also tried:
RewriteCond %{REQUEST_URI} !((adm[^/]+)/|ajax|google([a-z0-9])|tools|swf|confirm|style) [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L,NC]
RewriteCond %{REQUEST_URI} !/((.*)/adm/(.*)|ajax|google([a-z0-9])|tools|swf|confirm|style) [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L,NC]

Answer 1

Negative Lookahead
If I'm understanding correctly, the basic pattern you're looking for (with possible refinements) is:
adm(?![a-z])
(?![a-z]) is a lookahead that ensures that the following character is not a letter.
In mod-rewrite, you can make this case-insensitive with (?i)adm(?![a-z])

Answer 2

You can just add one more negative RewriteCond here to skip /adm/ URI from this rewrite:
RewriteCond %{REQUEST_URI} !/(adm|ajax|google([a-z0-9])|tools|swf|confirm|style) [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule !adm index.php [L,NC]

Answer 3

How about doing the opposite?
If it contains "/adm/" (including "slash") then stop
Otherwise redirect all to index.php
Like that:
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule (.*)/adm/(.*) - [QSA,L]
RewriteRule (.*) index.php [QSA,L]