功能动词，也叫轻动词(Light verb)，是一些普通动词在某些情况下独立出来拥有新的用法的一类特殊的动词，这类动词在句子中丢失了其自身的含义，而是需要与另一个实义动词性质的成分组合在一起构成复合动词，才能表现出完整的谓语意义。从功能动词的另一名字“轻动词”也可以看出它在构成复合动词的作用。

功能动词主要出现于德语当中，并且使用的频率非常高，这种动词在汉语和英语中也有所体现，但是在汉语中这样的动词较少，一般只会在官方场合才会出现，汉语功能动词总数约为10个左右。

注意：功能动词这一概念不应与德语强变化动词混淆，弱变化动词体现的是其在动词变位上不产生太大变化的特征，而功能动词是一类在使用时丢失原有实义动词的作用，仅起到形式与功能上的谓语作用，即只表现出时态、体貌以及语态等，这类动词与助动词有一定相似之处。

In linguistics, a light verb is a verb that has little semantic content of its own and forms a predicate with some additional expression, which is usually a noun. Common verbs in English that can function as light verbs are do, give, have, make, take, etc. Other names for light verb include delexical verb vector verb, explicator verb, thin verb, empty verb or semantically weak verb (a semantically weak verb is not to be confused with a weak verb of the Germanic weak inflection, however). While light verbs are similar to auxiliary verbs regarding their meaning contribution to the clauses in which they appear, light verbs fail the diagnostics that identify auxiliary verbs and are therefore distinct from auxiliaries.