"The word pani means dealer, trafficker, from pan (also pan, d. Tamil pan , Greek ponos, labour) .... " A footnote to pan reads:"Sayana takes pan in Veda - to praise, but in one place he admits the sense of vyavahara, dealing. Action seems to me to be its sense in most passages. From pan in the sense of action we have the earlier names of the organs of action, pani, hand, foot or hoof, Lat. penis, d. also piiyu."