Seddity (or saddity or siditty) – is defined as an African American who is bourgeois, snobbish or pretentious. According to Lisa J. Green’s study of the African American lexicon in African American English: a linguistic introduction, the usage of the word spanned from 1960 – 1980.[1]
As to the disparity in the spelling, this is attributed to certain lexical items being predominantly of oral context as opposed to spelling conventions in AAVE African American Vernacular English.[2]
Also, as part of AAVE, seddity/saddity/siditty is deemed as a people term[3] like words such as cuz and posse.