(history, weaponry) Little Boy

atomic bomb

a name (word or phrase indicating a particular person, place, class, or thing) / (more specifically) a given name (excluding the surname)

at first, firstly

first, the beginning, the start

the above / the top (position or direction) / the surface of / superior in skill, age, level, etc.

in addition; furthermore / on top of (which)

(only in compounds) being little

bomb / (fishery jargon) bivalve shell that contains mud instead of flesh

boy