köken: From pro- plus an element possibly derived from *peth₂- (“to rush, fly”), so that the original meaning was "falling or rushing forward", hence "eager, well-disposed". Compare Ancient Greek προπετής (propetḗs, “inclined forward”).
aile: propitiō
Sit utrīsque Venus Pompeiāna propitia et semper concordēs vīvant.