Completely still — not a step, not a turn of the head, nothing. It is stronger than 'still' on its own, and it carries a feeling with it: people usually stand stock-still because something has stopped them — fear, shock, listening hard, or trying not to be seen. That is why you meet it most in stories: he stood stock-still in the doorway; the deer froze stock-still at the sound.

Completely still完全靜止——not a step一步也不動，not a turn of the head頭也不轉，nothing什麼動作都沒有。It它 than 'still' on its own比單獨的 'still' is stronger更強，and it carries a feeling with it而且自帶一種情緒：people人 usually通常 stand stock-still會僵立不動，because是因為 something has stopped them有什麼讓他們停住了——fear恐懼、shock震驚、listening hard用力在聽、or trying not to be seen或想不被看見。That is why所以 you你 in stories在故事裡 meet it most最常遇到它：he stood stock-still in the doorway他一動不動地站在門口；the deer froze stock-still at the sound鹿一聽到聲音就僵住不動。

Grammatically it works as an adverb after a verb of stopping or holding position — stand, stay, sit, freeze, hold, remain — and it very rarely goes in front of a noun; you would not say 'a stock-still man' as easily as 'he stood stock-still'. It is written with a hyphen and both halves are stressed.

Grammatically文法上，it它 after a verb of stopping or holding position接在表示停住或保持姿勢的動詞後面 works as an adverb當副詞——stand、stay、sit、freeze、hold、remain——and it very rarely而且很少 goes in front of a noun放在名詞前面；you你 would not say說 'a stock-still man'，as easily as不像說 'he stood stock-still' 那麼自然順口。It它 with a hyphen帶著連字號 is written書寫，and both halves而且兩半 are stressed都要重讀。

It is not formal, but it is more a written, descriptive word than something you would say while chatting, and if you use it in speech it sounds a bit vivid, a bit story-telling.

It它 is not formal不算正式，but但 than something you would say while chatting比起聊天時會說的話，it它 is more更像 a written, descriptive word一個書面的、描寫用的詞，and if you use it in speech如果你在口語裡用它，it sounds聽起來 a bit vivid有點生動、a bit story-telling有點在說故事。