"Relentless bullying" refers to the continuous and persistent act of intentionally harming, teasing, or harassing someone repeatedly over a period of time. Full definition
«We see far too often in the media the devastating news of young people who have felt that suicide was the only option they had left after relentless bullying. (educationmattersmag.com.au)
In the most serious and tragic cases, some young people have taken their lives after relentless bullying and cyberbullying. (firemanlawyers.com)
There's a constant worry that you'll be called on in class, the terror of public speaking and, of course, the relentless bullying that comes with being a kid with a speech impediment. (entrepreneur.com)