Common words:
* deceive: To mislead or trick.
* decide: To make a choice or resolution.
* decrease: To become smaller or less.
* define: To state the exact meaning of something.
* delete: To remove something.
* demand: To ask for something firmly.
* depart: To leave a place.
* depend: To rely on someone or something.
* describe: To give an account of something.
* design: To plan or create something.
* desire: To want or long for something.
* destroy: To damage something beyond repair.
* develop: To grow or change over time.
* devote: To give all your time and energy to something.
* defeat: To overcome or beat someone in a competition.
* defend: To protect someone or something from attack.
* delay: To postpone something.
* deliver: To bring something to someone.
* deny: To refuse to admit something.
* depress: To make someone feel sad and hopeless.
* descend: To move down from a higher level.
* desert: To leave someone or something.
* detach: To separate something from something else.
* detect: To discover something.
* determine: To find out something for certain.
* develop: To grow or change over time.
* deviate: To change direction or course.
* devour: To eat something greedily.
* diagnose: To identify the cause of an illness.
Less common words:
* debase: To lower the quality or value of something.
* decamp: To leave a place suddenly.
* decipher: To decode or work out the meaning of something.
* declaim: To speak in a dramatic or formal way.
* decompose: To break down into simpler substances.
* deduct: To take away a certain amount from a total.
* defame: To damage someone's reputation.
* deficit: A shortage of something, especially money.
* deform: To change the shape of something, often in an unpleasant way.
* degrade: To lower the quality or value of something.
* dehydrate: To remove water from something.
* deject: To make someone feel sad or discouraged.
* delve: To investigate something thoroughly.
* denote: To indicate or represent something.
* depreciate: To decrease in value.
* deride: To make fun of someone or something.
* derive: To obtain something from another source.
* desolate: To make something empty and barren.
* despair: A feeling of hopelessness.
* despise: To hate someone or something.
* detach: To separate something from something else.
* deteriorate: To become worse.
* deter: To discourage someone from doing something.
* deviate: To change direction or course.
* devote: To give all your time and energy to something.
* diagnose: To identify the cause of an illness.
* differentiate: To distinguish between two or more things.
* diffuse: To spread out over a large area.
* digress: To stray from the main topic.
* dilute: To make something weaker by adding water or another substance.
* diminish: To become smaller or less.
* disclose: To reveal something that was previously secret.
* disdain: To look down on someone or something.
* disguise: To change someone's appearance to make them unrecognizable.
* dismantle: To take something apart.
* dismay: To make someone feel worried or disappointed.
* dismiss: To send someone away.
* disrupt: To interrupt or interfere with something.
* dissolve: To break down into smaller parts.
* distinguish: To tell the difference between two or more things.
* distract: To draw someone's attention away from something.
* distribute: To share something out among a group of people.
* diverse: Made up of many different types of people or things.
* divert: To change the direction of something.
* divine: Relating to God or gods.
* divorce: The legal ending of a marriage.
* document: To record something in writing.
* dominate: To have control over something.
* donate: To give something to a charity.
* dormant: Inactive but capable of becoming active again.
This list is just a starting point, and there are many more words that begin with the prefix "de". You can find more words by consulting a dictionary or thesaurus.