The meaning of the name Demarco is Of Marco. The origin of the name Demarco is American. This is the culture in which the name originated, or in the case of a word, the language.
From an Italian surname
Demarco is on 47 BN name lists Demarco is currently not ranked on the BN charts Demarco is currently #974 in U.S. births
Demarco 
