orexis
The affective and conative character of mental activity as contrasted with its cognitive aspect; the appetitive aspect of an act; desire, appetite.
A sweet orexis rising in his cock, a blush of fever mixing tickles in his balls, Adriaan slid his briefs off and began to lay out the makings for supper.
Where it comes from
From Latin orexis (“longing; appetite”), from Ancient Greek ὄρεξις (órexis, “desire”), from ὀρέγω (orégō, “to reach, stretch”).
Adapted from the Wiktionary entry orexis (CC BY-SA 4.0).