what is the significance of the name "scout" and "boo"?

I don't think that there are any clear textual explanations for these names. We can, however, make some suppositions. Consider Scout's penchant for exploring and adventure. She also analysis and interprets information much like her namesake. Arthur Radley is known as a ghoulish sort of figure, especially by the kids. It is possible that "Boo" represents this ghost like fiction they have cast upon the reclusive man.