Entry 2 senses · 2 variants Webster, 1913 Plantigrade · Plan·ti·grade · IPA /ˈplæntəˌɡɹeɪd/ a. n. 01 a. Walking on the sole of the foot; pertaining to the plantigrades. 1. Walking on the sole of the foot; pertaining to the plantigrades.(Zool.) 02 n. A plantigrade animal, or one that walks or steps on the sole of the foot, as man, and the bears. 1. A plantigrade animal, or one that walks or steps on the sole of the foot, as man, and the bears.(Zool.)