Here are some synonyms for "relentlessly":
* Persistently
* Incessantly
* Constantly
* Unwaveringly
* Tenaciously
* Ruthlessly
Here are some examples of how "relentlessly" is used:
* "The rain fell relentlessly throughout the night." (Meaning: The rain didn't stop or decrease in intensity.)
* "The athlete trained relentlessly for the marathon." (Meaning: The athlete trained hard and consistently.)
* "The company relentlessly pursued its goal of market dominance." (Meaning: The company worked hard and persistently to become the top competitor.)
In short, "relentlessly" means doing something without giving up or slowing down, no matter the difficulty.