Boston Celtics guard Jabari Bird choked out his girlfriend so badly during a Sept. 7th incident that she lost consciousness ... according to prosecutors.
24-year-old Bird appeared in court in Boston on Thursday where prosecutors laid out the case against him ... and the allegations are horrifying.
Officials say the alleged victim claims Bird terrorized her for 4 hours at her Brighton apartment -- where she tried to get away from the NBA player by hiding under her bed and locking herself in her bathroom.
During the alleged altercation, the woman claims Bird strangled her at least 12 times.