The Marketing Dictionary

Keyword density is the number of times a keyword appears within the content of a webpage.

Keyword stuffing is adding too many keywords beyond what is natural to a webpage to increase search rankings. This tactic is against Google's Webmaster guidelines and can be penalized by Google.

A keyword is the word or combination of words an SEO professional or marketer targets to find what users are searching for.

Keyword cannibalization is the self-competition occurs when more than one page from the same website ranks for the same or similar keywords.