The Collaborative International Dictionary
Gressorial
Gressorial \Gres*so"ri*al\, Gressorious \Gres*so"ri*ous\, a. [L. gressus, p. p. of gradi to step, go.] (Zool.) Adapted for walking; anisodactylous; as the feet of certain birds and insects. See Illust. under Aves.
Wiktionary
gressorial
a. (context zoology English) Adapted for walking.