all fours
Of a person, referring to one's hands and knees; of a four-legged animal, referring to all four feet. Typically used in the phrase "on all fours," a position in which one is on one's hands and knees. I got down on all fours and tried to find my ring in the sand. The bear got down on all fours and started charging at us through the trees.
all fours
All four limbs of an animal or person: a baby crawling on all fours.