run up on
To come across somebody or something unexpected, or to walk up on them sudden.
Also called run upon.
Updated September 24, 2026
run up on pronunciation
/run UP on/
Meaning
In rural Southern and Appalachian talk, run up on usually means you stumbled onto something: a snake, a still, an old buddy. DARE caught it for meeting somebody you had not seen in a while. The same words can mean you stepped up close in a tense way, like you run up on a man in a parking lot. Context tells you whether it was chance or confrontation.
How folks use it
- “We run up on a copperhead by the woodpile.”
- “I run up on my cousin at the feed store yesterday.”
Origin and etymology
Tied to older English run upon, meaning encounter or come across. In mountain speech upon softened to up on. DARE listed run up on among answers for meeting someone unexpectedly. Modern street slang sometimes uses the phrase for an aggressive approach; that sense travels, but the older rural meaning is chance encounter.
Frequently asked questions
Does run up on always mean a fight?
No. Around here it often just means you came across something by surprise. Tone of voice usually gives away the meaner sense.