I definied a new theorem via


But the text has a italic font and i do not want that. how can i deactivate the italic font?

  • 1
    What package are you using to create your theorems? – Werner Nov 22 '16 at 16:47
  • Aside: LaTeX won't let you set up an environment called def. You'll get an error message such as ! LaTeX Error: Command \def already defined.. Use defn or something else instead. – Mico Nov 22 '16 at 16:51
  • potential duplicate: Non italic text in theorems, definitions, examples – barbara beeton Nov 22 '16 at 16:55

I assume you're using a theorem-related package such as amsthm. If that's the case, just issue the instruction


ahead of the instruction


A full MWE:

\lipsum*[2] % filler text
  • If you use the ntheorem package rather than the amsthm package to set up theorem-like environments, you should replace \theoremstyle{definition} with \theorembodyfont{\upshape}. – Mico Nov 22 '16 at 16:56

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