Adam comes from the Hebrew word "adam" meaning "red blood" and is also related to "adamah" which means "ground, soil, red earth." Both of these make sense, because according to Genesis, Adam was formed from the dust of the adamah (red earth, clay) and all humans have one thing in common, they bleed the same red blood. It is used in the Old Testament to speak of humankind (male and female) or the singular person, Adam, depending on context.
The writers of the New Testament spoke of Adam as the name of a singular being, the first man (for example, Romans 5:14-15. "Nevertheless death reigned from Adam to Moses, even over them that had not sinned after the similitude of Adam's transgression, who is the figure of him that was to come.
But not as the offence, so also is the free gift. For if through the offence of one many be dead, much more the grace of God, and the gift by grace, which is by one man, Jesus Christ, hath abounded unto many.")