Separated from his mother when he was just an infant, the boy grew up in a children's home. She isn't able to look after herself at all - she's as helpless as an infant. In common terminology, a baby is the very young offspring of adult human beings, while infant (from Latin īnfāns 'baby, child', literally 'unspeaking') [1] is a formal or specialised synonym. The terms may also be used to refer to juveniles of other organisms. Infant cognitive development occurs in the Sensorimotor stage which starts at birth and extends until the infant is about 2 years of age. The sensorimotor stage is made up of six sub-stages. Infants primarily interact with the world through reflexes, such as sucking, grasping, and looking. The meaning of INFANT is a child in the first period of life. How to use infant in a sentence. The eldest of the comers, a girl who wore a triangular shawl, its corners draggling on the stubble, carried in her arms what at first sight seemed to be a doll, but proved to be an infant in long clothes. Different words are used for a baby at different stages of growth. These words are not used in the same way by everyone. For example, the word infant may be used until a baby can walk, or only until the baby is one year old. A baby from birth to about 3 months old is sometimes called a newborn. The term infant usually refers to a baby from birth to around 1 year of age. You may also use the term “baby” during this time or “newborn” for little ones up to around 3 months of age. Merriam-Webster defines an infant as a child in the first period of life but doesn't give any age specifics. It describes a baby as an extremely young child. Infant development: Birth to 3 months Infant development begins at birth. Consider major infant development milestones from birth to 3 months — and know what to do when something's not right. As a parent you give your children a good start in life—you nurture, protect, and guide them. Learn about developmental milestones, including emotional and social development, for babies from birth to 1 year of age. There are many things you can do to help your baby stay safe and healthy.