If you read the page you linked more carefully, you will see that OSI does not own a valid trademark for "Open Source", only for "Open Source Initiative". OSI

If you read the page you linked more carefully, you will see that OSI does not own a valid trademark for "Open Source", only for "Open Source Initiative". OSI in fact tried to file for a trademark on 'Open Source' in 1999 [1], but failed because the term is 'too descriptive'. [1] https://opensource.org/pressreleases/certified-open-source.php https://opensource.org/pressreleases/certified-open-source.p...