CONVERSION:

conversion
The process by which a word from one word class is used as if it belonged to another class. For example, glue started life as a noun, but is now frequently used as a verb. Many conversions are so common that we no longer notice them, but conversion is also a feature of creative uses of language:
‘I really have some severe doubts regarding this partnership,’ said he, upping and awaying.
It is often said that ‘there is no noun in English that can't be verbed’. (Tom McArthur)