"Itai" is a Japanese word that means "painful" or "ache". There are several synonyms that can be used in place of "itai" to convey similar meanings. Some of these synonyms include "kanashii" which means "sad" or "grieving". Another synonym is "tsurai" which means "difficult" or "painful". "Kurushii" is another option which means "agonizing" or "distressing". Other synonyms for "itai" include "kusai" which means "stinky" or "unpleasant" and "fukai" which means "deep" or "profound". These words can be used interchangeably depending on the context and the level of pain or discomfort being described.