Boy, in this context, refers to anyone with a connection to the word boy, regardless of if they mean binary boyhood or if they connect with boyhood in other forms, such as nymboys. The only specificity is that it is a queer and sapphic experience of both gender and attraction.
It is similar to lesboy.
History and Flags
Saphboy was coined by Tumblr user xenoleaf, October 9th, 2020. Two saphboy flags were created by the same user on the same date.
The term was recoined by FANDOM user Chaoticcylinder, via an edit to this article, who defined it as: "a boy that experiences their gender and attraction as sapphic. It can [refer] to a cusper sapphic person, a man aligned/solarian girl, a woman aligned/lunarian boy, girlboy/boygirl, a multigender person, sapphicgender man, or anyone else who has some connection to the word boy and identifies as sapphic."