"Board books" refer to a type of book designed for babies and young children. They are made with thick, sturdy pages that are difficult to rip or damage, making them suitable for little hands. Full definition
One of my first purchases after learning I was pregnant with my first child was a bunch of board books for my baby. (attachmentparenting.org)
For younger toddlers (12 to 24 months) you'll want sturdy board books with pictures (especially photos) of kids doing the things they do every day. (kidshealth.org)
Since the beginning, we have collected a lot of board books. (goldcoastgirlblog.com)