Definition of "compunctious"

Come, you spiritsThat tend on mortal thoughts, unsex me here;And fill me, from the crown to the toe, top-fullOf direst cruelty! make thick my blood,Stop up the access and passage to remorse,That no compunctious visitings of natureShake my fell purpose, nor keep peace betweenThe effect and it!

1606, Shakespeare, Macbeth, Act 1, Scene 5

Nothing can be conceived more hard than the heart of a thoroughbred metaphysician. It comes nearer to the cold malignity of a wicked spirit than to the frailty and passion of a man. It is like that of the principle of evil himself, incorporeal, pure, unmixed, dephlegmated, defecated evil. It is no easy operation to eradicate humanity from the human breast. What Shakspeare calls “the compunctious visitings of nature” will sometimes knock at their hearts, and protest against their murderous speculations. But they have a means of compounding with their nature. Their humanity is not dissolved. They only give it a long prorogation.

1796, Edmund Burke, A Letter to a Noble Lord