The chord symbol iii could be followed by the letter a to indicate that it is F# minor chord in root position (ie not inverted) - D major scale chord iiia. Instead, iii could be followed by the letter b to indicate that it is F# minor chord in 1st inversion - D major scale chord iiib.
According to the Centers for Disease Control and Prevention, a baby is considered an infant until he reaches one year of age. During this stage, the infant reaches several developmental milestones.
An infant is a baby. When you were an infant, you weren't able to walk, talk, or feed yourself (but you had a pretty mean burp). Infant is most often used for a very young human, but you can also use it to talk about animal babies. People are considered infants from the moment of birth until approximately one year old, an age when many babies are starting to walk and talk. At this point, they're commonly called toddlers instead of infants.