| odot | Text.LaTeX.Packages.AMSMath |
| OliveGreen | Text.LaTeX.Packages.Color |
| omega | Text.LaTeX.Packages.AMSMath |
| omegau | Text.LaTeX.Packages.AMSMath |
| ominus | Text.LaTeX.Packages.AMSMath |
| OneColumn | |
| 1 (Data Constructor) | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| 2 (Data Constructor) | Text.LaTeX.Packages.Hyperref |
| onecolumn | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| OneSide | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| oneside | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| OneSlide | Text.LaTeX.Packages.Beamer |
| only | Text.LaTeX.Packages.Beamer |
| onslide | Text.LaTeX.Packages.Beamer |
| Opaqueness | |
| 1 (Type/Class) | Text.LaTeX.Packages.Beamer |
| 2 (Data Constructor) | Text.LaTeX.Packages.Beamer |
| OpenAny | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| openany | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| OpenRight | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| openright | Text.LaTeX.Base.Commands, Text.LaTeX.Base, Text.LaTeX |
| operatorname | Text.LaTeX.Packages.AMSMath |
| oplus | Text.LaTeX.Packages.AMSMath |
| OptArg | Text.LaTeX.Base.Syntax |
| Orange | Text.LaTeX.Packages.Color |
| OrangeRed | Text.LaTeX.Packages.Color |
| Orchid | Text.LaTeX.Packages.Color |
| oslash | Text.LaTeX.Packages.AMSMath |
| OT1 | Text.LaTeX.Packages.Fontenc |
| otherLangs | Text.LaTeX.Packages.Babel |
| otherlanguage | Text.LaTeX.Packages.Babel |
| otimes | Text.LaTeX.Packages.AMSMath |
| OverlaySpec | Text.LaTeX.Packages.Beamer |
| overline | Text.LaTeX.Packages.AMSMath |
| overprint | Text.LaTeX.Packages.Beamer |