In grammar, a supine is a form of verbal noun used in some languages. The term is most often used for Latin, where it is one of the four principal parts of a verb.
The word also refers to a position of lying on one's back (as opposed to 'prone', lying face downward), but there exists no widely accepted etymology that explains why or how the term came to be used to also describe this form of a verb.
Latin
There are two supines, I (first) and II (second). They are originally the accusative and dative or ablative forms of a verbal noun in the fourth declension, respectively.
First supine
The first supine ends in -um