Zealous is an adjective that describes a person or thing that shows great enthusiasm, passion, or devotion for a cause, goal, or belief. It implies a strong emotional or spiritual commitment to something.


US English

UK English

Part of Speech



Enthusiastic, passionate, fervent, eager, devoted, ardent, dedicated, committed, fanatical.


Apathetic, indifferent, unenthusiastic, disinterested, cool, uncommitted, half-hearted.

Word Forms

Part of Speech Words
Noun zeal, zeals
Verb None
Adjective zealous
Adverb zealously

Example Sentences

  • The zealous fans cheered their team on during the entire game.

  • Sarah is a zealous advocate for animal rights and spends most of her free time volunteering at the animal shelter.

  • The new employee was so zealous in his work that he often worked overtime to ensure everything was perfect.

  • Some people become so zealous about their religious beliefs that they may not tolerate any differing opinions or practices.


The word zealous is often used to describe a person or a group of people who are strongly committed to a particular cause, belief, or activity. This commitment is usually displayed with a high level of enthusiasm and energy, and the person may be willing to go to great lengths to promote or defend their cause. A person who is zealous about their work, for example, may be willing to work long hours or go above and beyond what is expected to ensure a successful outcome.

Zealous can also be used in a negative context, particularly when describing people who are excessively or fanatically devoted to a cause. In such cases, the person’s zealousness may be seen as extreme, and their behavior may be considered irrational or harmful. For example, someone who is zealous about a political or religious cause may become intolerant of those who do not share their beliefs, leading to conflicts or even violence.

The word zealous comes from the Greek word zelos, which means ardor or fervor. It is often used with prefixes such as over-zealous or under-zealous to emphasize the degree of enthusiasm or dedication. For example, someone who is over-zealous may be seen as excessively enthusiastic or even obsessive, while someone who is under-zealous may be seen as lacking enthusiasm or motivation. Overall, the word zealous is often used to describe a strong, positive commitment to a cause, but it is important to use it with care to avoid negative connotations or misunderstandings.