Meta-tag stuffing
 

This involves repeating keywords in the Meta tags, and using meta keywords that are unrelated to the site's content. This tactic has been ineffective since 2005.

Meta-tag stuffing is considered as an unethical black hat SEO technique.

thanks for such a useful information

Meta tag stuffing refers to the usage of too many keywords in meta tags.

Meta tags stuffing is black hat technique and everyone should avoid it to get benefits from google for example if 65 words are allow in title you should avoid to exceed this limit and if meta description limit is 155 you should avoid to exceed it.

The repetition of keywords in meta tag is called keywords stuffing. It should be 2-3% only.