presumptuous
Pronunciation: /prɪˈzʌm(p)tʃʊəs/
adjective

Origin:
Middle English: from Old French presumptueux, from late Latin praesumptuosus, variant of praesumptiosus 'full of boldness', from praesumptio (see presumption)

Spelling help
Remember that presumptuous is spelled with a p after the m; the ending is -uous.