The word **出乎** is a classical Chinese-derived compound, formed by combining the verb **出** (chū, "to go out" or "to exceed") with the classical prepositional particle **乎** (hū, which functions similarly to "from" or "than," indicating a source or point of comparison). Together, they create a two-character unit meaning "to go out from" or "to exceed the scope of," almost always used in the fixed, idiomatic structure **出乎...之外/意料** (chūhū...zhīwài/yìliào), meaning "to go beyond (something)" or "to be unexpected/exceeding expectations." Thus, its formation is grammatical, where 乎 links the action of "exceeding" to its target or benchmark.