noun
sitting with legs splayed out, bottom on the ground
A sitting posture similar to seiza but with both legs spread outward and the buttocks resting directly on the floor. Often considered a less formal or more relaxed alternative to seiza.
See also: 正座 (せいざ)
長時間の正座がつらいときは、鳶足で座る人もいる。
When sitting in seiza for a long time is painful, some people sit in tonbiashi.
鳶足は正座より楽だが、正式な場ではあまり使われない。
Tonbiashi is more comfortable than seiza, but it is not often used in formal settings.