I'm the person who coined the term ADOAS (in a Dreamwidth journal that has since been deleted). It stands for American Decendent of African Slaves. I intended it to represent an ethnic group, and, in particular, to classify people of African heritage in a way that distinguishes between those who have inherited the legacy of slavery in the USian context and those who have not. (It could be further specified as NADOAS, the "N" representing North, to differentiate between North and South America.
The term is, loosely speaking, an alternative to the problematic term "black" or "black American," which is problematic because whitey, the oppressor, created the concept of blackness as it currently exists in the United States (and hopefully ADOAS do not wish to identify with whitey's racist creations). However, it is not a true alternative because it is an ethnic group whereas "black" is a racial category. Race and ethnicity overlap but are not the same thing. Race generally only has meaning, at least in the contemporary United States, in the context of racism, whereas distinct ethnic groups exist regardless of sociopolitical context. The significance of avoiding blackness as an identity is that by doing so, one avoids identifying with an ideological tool of racist oppression.
I just watched a video in which someone used the term ADOAS. He said "ADOAS black person," which is a misuse of the term in that the whole point of the term is to reject blackness as a personal identity.
I'm always a bit surprised to come across people using this term, since I wrote about it on this obscure corner of the Internet. But since it's now out there and the original writing has been deleted, I want to set the record straight. I'll probably write more about this at another point.