You might be thinking of:
* "dent-": This prefix means "tooth" and is derived from the Latin word "dens". It's used in words like:
* Dental: Relating to teeth.
* Dentist: A doctor who specializes in teeth.
* Dentition: The arrangement of teeth.
* "de-": This prefix can mean "away from", "down", "off", or "removal". It's a very common prefix used in many words, like:
* Departure: The act of leaving.
* Decrease: To become smaller.
* Decompose: To break down.
If you're trying to understand a particular word, it's helpful to look at its full meaning and etymology to figure out the specific prefix being used.