The adjective 足 (zú) means "sufficient," "enough," or "ample," and it also means "foot" as a noun. In literary and idiomatic usage, it often conveys the sense of being adequate or complete, as in the idiom 画蛇添足 (adding feet to a snake — doing something superfluous and ruining the result). It appears frequently in formal or written Chinese.
这些证据还不足以说明问题。
Zhèxiē zhèngjù hái bù zúyǐ shuōmíng wèntí.
This evidence is not yet sufficient to explain the problem.
画蛇添足反而把事情搞砸了。
Huà shé tiān zú fǎn'ér bǎ shìqing gǎo zá le.
Gilding the lily actually ruined the whole thing.
我们的准备已经足够充足了。
Wǒmen de zhǔnbèi yǐjīng zúgòu chōngzú le.
Our preparations are already more than sufficient.