A young child who has started walking but not fully mastered it, typically between one and three years old.
"The toddler wobbled unsteadily as he took his first steps away from the sofa."
In plain English: A toddler is a very young child who has just started walking but still needs help with many daily tasks.
"The toddler dropped his ice cream cone on the sidewalk."
Usage: Use toddler to refer specifically to children aged roughly one to three years who are learning to walk or have recently begun walking independently. This term distinguishes them from infants who cannot yet stand and older preschoolers who have full control over their gait.
The word toddler comes from the verb to toddle, meaning to walk unsteadily, combined with the suffix -er. It was originally used to describe someone who walked in this manner before coming to refer specifically to a young child.