The word basil comes from the Greek Î Î Ï Î Î '' Î Ï Ï ( basileus ) , meaning `` royal '' . This is because it is believed to have grown above the spot where St. Constantine and Helen discovered the Holy Cross . The word basil comes from the Greek Î Î Ï Î Î '' Î Ï Ï ( basileus ) , meaning `` king '' , as it is believed to have grown above the spot where St. Constantine and Helen discovered the Holy Cross .