From pretentious + -ly.

• (RP) IPA: /pɹɪˈtɛnʃəsliː/, /pɹəˈtɛnʃəsliː/
• (America) IPA: /pɹɪˈtɛnʃəsliː/, /pɹiːˈtɛnʃəsliː/

pretentiously

1. In a manner with unwarranted claim to importance or distinction.
2. Ostentatiously; in a manner intended to impress others.
   • 1914 November, Louis Joseph Vance, “An Outsider […]”, in Munsey's Magazine, volume LIII, number II, New York, N.Y.: The Frank A[ndrew] Munsey Company, […], published 1915, →OCLC ↗, chapter I (Anarchy), page 373 ↗, column 2:

     Little disappointed, then, she turned attention to "Chat of the Social World," gossip which exercised potent fascination upon the girl's intelligence. She devoured with more avidity than she had her food those pretentiously phrased chronicles of the snobocracy—[…]—distilling therefrom an acid envy that robbed her napoleon of all its flavor.

3. In a manner demanding of skill or daring.

• pretentious
• pretentiousness

• French: prétentieusement
• Italian: pretenziosamente
• Portuguese: pretensiosamente
• Spanish: pretenciosamente