A considerable amount of money; a high price or a high income.(noun)
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Use "pretty penny" in a sentence
"I took her to one of those enormous, modernistic palaces, all glass and stainless steel, that are springing up all over the West End; we had a couple of adjoining rooms there on the third floor, and paid a pretty penny for them."
"Ayeeyah, it is going to cost Lincoln Bartlett a pretty penny for daring to stick this … this creature upon us, he promised himself."