Backed up is commonly used to describe a situation where something is stuck or has come to a halt. Some alternative words that can be used to convey the same meaning includes congested, jammed, blocked, obstructed, clogged, and stalled. These words could apply to situations like traffic, plumbing, computer files, or even a digestive system, where things are moving slowly or not at all. Another common synonym for backed up is 'delayed', which might be used in a business or academic context when a project is behind schedule. These words are especially important to keep in mind when trying to convey a sense of urgency or frustration.