散々 translated literally means “scatter, scatter” as the character 散 itself means “to scatter” and 々 is a shorthand symbol we use for repeat the sound of the word before it. Figuratively, 散々 is used to express the degree or extent of how bad something is - in English, we’d generally translate this as “terrible” or “awful”.
散々 works as a な-adj. For example, if we say 散々な日 (日 here means “day”), then that would mean “a terrible day”. 散々 can also work as an adverb. Sometimes に is attached after 散々, e.g. 散々に. When used as an adverb, though, it can’t be used to modify other adjectives in an attempt to extend their meaning - so for example, saying 散々大きい to mean “terribly big” would not be correct.
散々 often has a negative connotation, but sometimes we use this word to simply express the meaning of “a lot” or “throughly”. such as パーティーで散々食べた (“I ate ‘a terrible amount of food’ (a lot) at the party”. However, this type of usage is a bit tricky, so it is better to use it when describing an action you take for yourself, and not for actions that involves the others, as it may be taken the wrong way!
The result of the JLPT test was terrible.
Mayumi trash talks an awful lot, and that makes me nervous.