To tenderize meat is to do something to it before cooking so that it turns out soft instead of tough to chew. There are several ways, and the word covers all of them: hitting the meat with a heavy mallet to break the tough fibres, cutting into it, soaking it in a marinade with something acidic such as vinegar, wine, or pineapple juice, rubbing salt or a powder into it, or simply leaving it to hang and age. So the word describes a purpose, not one technique. It is a practical, everyday kitchen word — recipes, cooking shows, butchers, restaurant kitchens — and it is fully ordinary, not formal at all. British writing usually spells it tenderise; American writing uses tenderize. Both are correct in their own place. People also use it playfully outside the kitchen, for hitting someone or something repeatedly: a boxer 'tenderizing' his opponent's ribs, or a long argument 'tenderizing' someone until they finally agree. That use is a joke built on the mallet image, and it is common enough that you will meet it. One thing worth knowing: tenderizing is not the same as cooking gently for a long time. Slow cooking also makes meat soft, but tenderizing means the preparation you do beforehand. A cook would say 'I tenderized the beef, then fried it quickly.'

（把肉）弄軟、拍鬆、醃軟；台灣廚房常說「把肉拍鬆」或「醃過讓肉比較嫩」