Ithyphallus is a term that refers to an erect penis, particularly in ancient Greek and Roman art and literature. While this word may be appropriate in certain contexts, there are several synonyms that can be used to describe the same thing. Some possible synonyms include phallus, erect member, hard-on, boner, and engorged organ. Other options may include more euphemistic terms such as tumescent shaft, throbbing member, or stiff rod. Ultimately, the choice of language will depend on the context and tone of the communication, as well as the preferences of the audience.