expression, ichidan verb
duck one's head; pull one's head in
Describes the physical action of drawing one's head down or in, often to avoid something or out of fear.
ボールが飛んできたので、とっさに首を縮めた。
A ball came flying, so I instinctively ducked my head.
叱られて、彼は首を縮めて小
Being scolded, he pulled his head in and shrank.