directional, noun, preposition, abbreviation, place word · the outer part, side, or area of something; exterior

教室外有一棵高大的树。

verb, directional · belonging to the outward part or relating to outside connections

这种药水只能外用，不可内服。

abbreviation, verb, place word, expression, noun · relating to or originating from a country other than one's own

他利用假期去国外旅游。

directional · beyond a certain scope, limit, or quantity; besides

除了这支笔以外，我还需要一个笔记本。