Repeating something by heart means that you are memorizing it or reciting it from memory. There are several synonyms that can be used interchangeably with this phrase. One common synonym is "commit to memory," which indicates the act of placing something in your memory for future use. Another possible synonym is "learn by rote," which typically implies memorizing something through repetition. You can also use the phrase "memorize by heart" as a synonym, which similarly implies the act of storing something in your memory. Ultimately, while there are several different synonyms for "repeat by heart," they all convey the same concept of memorizing through intentional effort.