Level Seven, Department of Magical Games and Sports, incorporating the British and Irish Quidditch League Headquarters, Official Gobstones Club and Ludicrous Patents Office.
Utterly nonplussed, he looked around at the others, who were now laughing at the expression on Ron’s face and at the ludicrously prolonged laughter of Luna Lovegood, who was rocking backwards and forwards, clutching her sides.
It’s forty-ten, forty-ten to Slytherin and Pucey has the Quaffle Harry could hear Luna’s ludicrous lion hat roaring amidst the Gryffindor cheers and felt heartened; only thirty points in it, that was nothing, they could pull back easily.
There are no more uses of "ludicrous" in the book.
Show samples from other sources
Though she was serious, her suggestion was so ludicrous, I couldn’t suppress a laugh.
In Zimbabwe inflation reached the ludicrous level of 231 million per cent.