Here are some possibilities:
* "Irritant" is a common word meaning something that causes irritation. This could be a simple typo.
* "Irrigant" is a less common word meaning something that is used to irrigate (water or cleanse). This could be a misspelling related to the medical field.
* "Agent" is a common word meaning a person or thing that acts or produces an effect. This might be relevant if the word was used in a specific context.
Could you please provide more context about where you encountered this word? Knowing the context will help me figure out the intended meaning.