Noun, A term of endearment,toward a young child,usually African American.It's especially used in Baltimore, by single,unattached mothers to convey not only tender affections, but family status, upon the young infant,and preschool sons, who are their nearly constant companions.Origin of this definition may be from the Hannah Barberra cartoon,Yogi Bear, in which Yogi is befriended by his cute, but wise,little sidekick BooBoo, with whom he has a close, bumbling but kind,paternal relationship.
Ain't no gentlemen o' dis ho(u)se, but my Boo,Damone,is his Momma,s lil' man.
boo is a term that is derived from the French word "beau" meaning beautiful. In 18th century England it meant an admirer, usually male. It made it's way into Afro-Caribean language perhaps through the French colonisation of some Caribean islands.