Common words:
* Extraordinary: Exceptional; remarkable.
* Extrovert: A person who is outgoing and enjoys socializing.
* Extract: To remove or take out.
* Extracurricular: Activities that are not part of the regular curriculum.
* Extravagant: Spending money or using resources freely and recklessly.
* Extrasensory: Pertaining to senses beyond the normal five.
Less common words:
* Extralegal: Outside the law or legal process.
* Extrapolate: To estimate or conclude something by extending known information.
* Extremist: A person who holds extreme views.
* Extraneous: Irrelevant or unrelated.
* Extraterrestrial: Originating or existing outside the Earth.
* Extradition: The legal process of transferring a person accused of a crime to another country.
Informal words:
* Extra: Something additional or supplementary.
* Extra cheesy: Excessively cheesy or sentimental.
Let me know if you'd like more words or examples!