I'm sorry, I didn't realize the name change would make a difference, and I had already had that define by that name in my file. I re-did it exactly as you said, and it *did* work just fine.

The only problem now is that it's putting the phrase "Custom Keywords" at the end of the keywords list as such:

"dog bowtie, bow tie for dogs, black, red, large, small CUSTOM_KEYWORDS"

The EXACT line I have in the meta_tags.php in the english folder is:

define('HOME_PAGE_META_KEYWORDS', 'dog clothes, accessories, dog supplies, collars, dog beds, small dog carriers, travel, pet, puppy');

And the EXACT code in my meta_tags.php file in modules:

case ($this_is_home_page):
define('META_TAG_TITLE', (defined('NAVBAR_TITLE') ? NAVBAR_TITLE . PRIMARY_SECTION : '') . TITLE . TAGLINE);
define('META_TAG_DESCRIPTION', HOME_PAGE_DESCRIPTION);
define('META_TAG_KEYWORDS', HOME_PAGE_META_KEYWORDS);
break;


I used the Developer's Tool Kit in Admin to see if I could find where the "CUSTOM_KEYWORDS" might be located, and here is where it's showing up:

/includes/languages/english/meta_tags.php
Line #12 : //define('CUSTOM_KEYWORDS', 'ecommerce, open source, shop, online shopping');

/includes/languages/english.php
Line #16 : define('CUSTOM_KEYWORDS', 'ecommerce, open source, shop, online shopping');

includes/modules/custom/meta_tags.php
Line #51 : define('KEYWORDS', str_replace('"','',zen_clean_html($keywords_string_metatags) . CUSTOM_KEYWORDS));

Line #243 : $metatags_keywords = $product_info_metatags->fields['metatags_keywords'] . METATAGS_DIVIDER . CUSTOM_KEYWORDS; // CUSTOM skips categories

Line #251 : define('META_TAG_KEYWORDS', str_replace('"','',$metatags_keywords)); // KEYWORDS and CUSTOM_KEYWORDS are added above

/includes/modules/meta_tags.php
Line #51 : define('KEYWORDS', str_replace('"','',zen_clean_html($keywords_string_metatags) . CUSTOM_KEYWORDS));

Line #238 : $metatags_keywords = $product_info_metatags->fields['metatags_keywords'] . METATAGS_DIVIDER . CUSTOM_KEYWORDS; // CUSTOM skips categories

Line #246 : define('META_TAG_KEYWORDS', str_replace('"','',$metatags_keywords)); // KEYWORDS and CUSTOM_KEYWORDS are added above


Which of these do you think are causing problems? I haven't bothered the english.php file, and i'm using the overrides folder for the meta_tags.php files.
I'm thinking that one of them may be something to do with the original define I had in english.php (which is why I mis-named it before) but can't find the tutorial i used to make the changes before you started working with me so couldn't say which one.