Yes it does. Starting out with name calling and nastiness and escalating to violent assaults that target only the OPs son. Sounds like classic bullying to me.
I was very quiet and bullied the entire time I was at secondary school and half of primary. Not a single one of them stopped without violence.
One stopped after my mother collared him, took his phone and rang his parents and told them to come and get him and sort him out. They did and his father gave him a wallop and told him if it happened again he'd be sorry. It didn't.
Bully number two was waylaid by my older cousin and told to leave me alone. He didn't, my cousin came back and punched him and he stopped.
Bully number 3 was the worst and pushed me under a bus, shoved me down spat on me, didn't give a shit about the teachers, police talking to him, his parents didn't care. My dad put a stop to him after the bus incident. Followed him, caught him hurting me, grabbed him by the throat and told him if he saw him near me again he'd kill him. Guess what? He stopped.
4th Bully I eventually stood up to myself. Aggressively. He went to A&E and never touched me again.
All this was after years of raising with the school, police etc and getting nowhere.
They speak one language. Just tell him to hit back.