Lewis Short
po
* Insep. prep. (cf. ποτί, πρός), a prefix denoting power or possession, or that renders emphatic the meaning of a verb; as in polleo, polliceor, pono.
* ‡ po pro potissimum positum est in Saliari carmine, Fest. p. 205 Müll.
Charlton T. Lewis, Charles Short, A Latin Dictionary