Common words:
* Attitude
* Altitude
* Fortitude
* Gratitude
* Latitude
* Longitude
* Magnitude
* Multitude
* Solitude
Less common words:
* Aptitude
* Beatitude
* Certitude
* Fiduciary (though this word is technically a noun, it's derived from "fiducia," meaning trust)
* Fertitude
* Frivolitude
* Lassitude
* Magnitude
* Multitude
* Rectitude
* Servitude
* Similitude
* Solicitude
* Temperament (though not strictly ending in "-tude", it shares the root)
* Virtuosity
Note: Some of these words, like "temperament", share the same root but don't end in "-tude" directly.
The suffix "-tude" usually indicates a state, quality, or condition. It's often used to create abstract nouns.