永 is a formal or literary adverb that means 'forever' or 'perpetually'. It is more concise than 永远 and typically appears directly before a monosyllabic verb in fixed or elevated expressions, such as 永存 ('last forever'), 永别 ('part forever'), or 永驻 ('abide forever'). You will find 永 in idioms, written language, and official proclamations rather than in everyday spoken Chinese.