Here are some words with the prefix "alti-":
* Altitude: The height of an object above sea level or another reference point.
* Altimeter: An instrument that measures altitude.
* Altissimo: The highest part of a singer's or instrument's range.
* Altocumulus: A type of cloud formed at a high altitude.
* Altostratus: Another type of cloud formed at a high altitude.
Let me know if you'd like more examples!