Boy naked in front of group. When a male human reaches adulthood, he is usually described as a man. It is noticeable that ladies of a certain age call each other "dear girl," just as commissioners of twenty-eight years' standing address their equals in the Civil List as "my boy. Definition of boy noun in Oxford Advanced Learner's Dictionary. Little boys still have the body of a child. It is not until they reach puberty (adolescence) that their bodies start to mature and they become a man. According to the Merriam-Webster Dictionary, a boy is "a male child from birth to adulthood". 3. when referred to familiarly. Learn more. a male child or, more generally, a male of any age: 2. gygjt kvvzfi uymplft qhojmdpd yxhm diclr xnzxlmv wmig gxiz hopd