shape of the kanji 大; spread-eagled; sprawling
Describes a person lying with arms and legs outstretched, resembling the shape of the kanji 大. Often used with verbs like 寝る, 倒れる, or なる.
Exhausted, I sprawled out on the bed.
He was lying spread-eagled on the floor.
From the visual resemblance of the kanji 大 (big) to a person with outstretched arms and legs.