What does overrun mean?
Overrun means to go beyond an expected boundary, limit, or area, usually with the result that something becomes excessive or difficult to control. The verb is often used for people, animals, or plants taking over a space, as in weeds overrunning a garden, and for costs or deadlines exceeding expectations, as when a project overruns its budget. It can also carry a military or territorial sense, describing an advancing force occupying an area. The word is formal and often suggests an uncontrolled or unwelcome expansion, although it can simply indicate that a numerical limit has been exceeded. In technical computing contexts, an overrun occurs when data or processing extends beyond the space reserved for it. Overrun is therefore useful wherever one needs to describe not merely a large quantity, but a boundary that has been crossed and possibly a situation that has become difficult to manage.
To swarm over or occupy a place in large numbers; to overwhelm or extend beyond a limit.
"The crowd overran the barriers and entered the track."
Commonly used with objects such as 'a place,' 'a budget,' 'a deadline,' or 'a region.'
An instance in which a limit, boundary, or available space is exceeded; an excessive or uncontrolled spread.
"The overrun in the final quarter forced the company to revise its forecast."
Less common than the verb; often used in financial, technical, or administrative contexts.
Having exceeded an allotted limit or boundary, especially in computing or technical contexts.
"The program detected an overrun buffer and stopped before the data could be corrupted."
Usually used in technical expressions such as 'overrun buffer' or as the participial form of the verb.
The plural is used for separate instances or occurrences of exceeding a limit, spreading beyond a boundary, or financial overruns.
"The company reported several budget overruns during the first year."
To overrun something is to go beyond its limits—and sometimes, as with weeds, there is no obvious way to stop the spread.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does overrun come from?
The word is a compound formed in English from the prefix over- and the verb run. Its earliest sense referred to running or extending beyond a limit, and the modern uses developed from that idea of excess and encroachment. The prefix over- has Old English roots and expresses movement beyond a normal or permitted boundary, while run has roots in Old English rinnan, meaning to move swiftly or travel.
Related word forms
How overrun is actually used
The verb is transitive and commonly appears in passive forms such as 'overrun by' or 'overrun with.' In computing, 'overrun' can refer to data or a process exceeding an allocated buffer or limit.