The term "infant" derives from the Latin word in-fans, meaning "unable to speak." There is no exact definition for infancy. "Infant" is also a legal term with the meaning of minor; that is, any child under the age of legal adulthood.
A human infant less than a month old is a newborn infant or a neonate. The term "newborn" includes premature infants, postmature infants and full term newborns.
Upon reaching the age of one or beginning to walk, infants are subsequently referred to as "toddlers" (generally 12-36 months). Daycares with an "infant room" often call all children in it "infants" even if they are older than a year and/or walking; they sometimes use the term "walking infant".
