What does the word "acrimonious" mean?

If I met a working man and his wife in the streets between eleven o'clock and midnight on their way home from the Ambigu Comique, I used to amuse myself by following them from the Boulevard du Pont aux Choux to the Boulevard Beaumarchais. The good folk would begin by talking about the play, then from one thing to another they would come to their own affairs, and the mother would walk on and on, heedless of complaints or question from the little one that dragged at her hand, while she and her husband reckoned up the wages to be paid on the morrow, and spend the money in a score of different ways. Then came domestic details, lamentations over the excessive dearness of potatoes, or the length of the winter and the high price of block fuel, together with forcible representations of amounts owing to the baker, ending in an acrimonious dispute, in the course of which such couples reveal their characters in picturesque language. As I listened, I could make their lives mine, I felt their rags on my back, I walked with their gaping shoes on my feet; their cravings, their needs, had all passed into my soul, or my soul had passed into theirs. It was the dream of a waking man. I waxed hot with them over the foreman's tyranny, or the bad customers that made them call again and again for payment.