What is the Synonym for controlled variable?

There isn't one single perfect synonym for "controlled variable," but here are some options depending on the context:

General synonyms:

* Constant variable

* Fixed variable

* Independent variable (though this is typically used in a broader sense)

* Standardized variable

More specific synonyms:

* Held constant (when referring to the action of controlling the variable)

* Unchanged variable (emphasizing that the variable remains the same)

* Manipulated variable (if the variable is being changed in a controlled way)

* Controlled factor (if emphasizing the broader context of a controlled experiment)

The best synonym will depend on the specific context of your sentence and what you are trying to emphasize.