^ âeucatastropheâ (US) / âeucatastropheâ (UK) in Oxford Dictionaries, Oxford University Press.
For cooked onions, you can find one answer here: http://www.stilltasty.com/fooditems/index/17825. 1  3-5 days in the refrigerator. 2  refrigerate withing 2 hours of cooking. 3  refrigerate in covered container or wrap tightly with heavy-duty aluminum foil or plastic wrap.
After being cut, onions can be stored in the refrigerator in a sealed container for up to 7 days. A widely circulated claim states uncooked, leftover onions are 'poisonous' because they're 'a huge magnet for bacteria,' thus likely to spoilage.