zú​zú

extremely

足足 zú​zú
extremely descriptive
to a very high degree; thoroughly

The preparations this time were more than thorough.

fully adverb
no less than; as much as (usually indicating a large amount or duration)

He waited for a full three hours.

Frequency

Movie subtitles
3.67 per million appears in 2% of films
Written text
7.30 per million

Sources

Definitions
CC-CEDICT