What is the meaning of the Phrase 'At Large'.

Rule of thumb' means - Fill in the gap: Birds fly ___ in the sky. One's finger prints are- To keep the wolf away from the door’ means— Which is the meaning of the idiom- 'to smell a rat'? Take somebody to task ___ the meaning of this idiom is - 'A burning question’ means – The Idiom 'Dead Letter' 'Bolt from the blue' means- ‘De facto’ means –