GBH is a British legal short form for grievous bodily harm: the crime of attacking someone and hurting them badly — broken bones, serious wounds, lasting damage, not a passing bruise. Police, courts, and newspapers in England, Wales, and Northern Ireland say GBH; people also say it in everyday talk after a nasty fight (“he got done for GBH”). It is heavier than ABH, actual bodily harm, which is real injury but less grave. There is a still more serious kind where the attacker meant to cause that grave harm. The word grievous just means very serious; students need the letters, not a fancy style. US English does not really use GBH; they talk about assault instead. Saying the letters G-B-H is the normal way; it is not read as a word.