The Internet of Things is reshaping many households' digital landscape and influencing children's play and learning, especially in the form of toys that are named the Internet of Toys (IoToys). IoToys may generate a significant influence on children's growth. While increasing attention is drawn to the IoToys, confusion around their conceptualization and use is evident. Without a thorough understanding of what the IoToys are, the progress of meaningful research on this topic will be greatly hindered. We, thus, conducted a systematic review to determine existing definitions of the IoToys using seven major databases over the past 20 years. After analyzing the definitions identified, we found that the previous definitions neglected the significance of defining "toys" in their work. The review led to a discussion around how to understand "toys" and then a more precise conceptualization of the IoToys, based on which implications for future research are offered.