also: さそく
He kicked the ball with his left foot.
left leg
Refers to the entire left leg, from hip to foot. Often used when the distinction between foot and leg is not important, or when context makes it clear.
I broke my left leg.
My left leg is numb.
The soccer player kicked the ball with his left foot.
He fractured his left leg while skiing.
I make it a habit to put my shoes on starting with my left foot.
Alternative spelling using 脚, which emphasizes the leg rather than the foot. Less common than 左足.