There are multiple origins and meanings for the name:
1. French, Portuguese and Russian (Денис), from Greek (Δενις) meaning - "follower of Dionysus"
2. Derived from the Turkish (Turkic) word (deniz) meaning - "sea"
Saint Denis - is a Christian martyr and Saint. In the third century, he was Bishop of Paris. He was martyred in approximately A. D. 250: after his head was chopped off, Denis is said to have picked it up and walked six miles, preaching a sermon the entire way, making him one of many cephalophores in hagiology. He is venerated in the Roman Catholic Church as patron of Paris, France and as one of the Fourteen Holy Helpers.