bouncing       
adjective [ before noun ] uk/ˈbaʊn.sɪŋ/ us/ˈbaʊn.sɪŋ/
 (尤指婴儿)健壮的,活跃的,精力旺盛的
(especially of a baby) healthy and energetic
  We've got two grandchildren - a three-year-old girl and a bouncing baby boy. 我们有两个孙辈的孩子——一个3岁的女孩和一个健壮的男婴。