A combination of Nub (aka noob/newb etc.) and the human+male+hunter class 'HUmar' in the game 'Phantasy Star Online'. Nubmar usually refers to a HUmar played by a person who severely lacks skill, knowledge how to play properly, dies a lot, plays at most five out of the dozens of available quests and has very generic equipment.
The HUmar class is often the first picked by beginners new to the game and to add insult to injury, there is an abundance of FF7 fanboys who name their character Sephiroth thinking they are original when in fact they are the hundredth person to do so. This has led to the name becoming iconic and players with the name will automatically be considered Nubmar.
Due to the poor image of the class caused by many poor players, some veterans and experienced players also call the class itself Nubmar.
Other variants are Noobmar/n00bmar.
"Man, I just did a West Tower run with this Nubmar. He died 7 times!"