muck up
In real, traceable use. Part of the curated seed collection; community review is coming.
Sense 1
Meaning · English
To ruin unintentionally.
Register: informal
Where it’s used:
Used
American English
Examples
The terrorists have really mucked up our holiday plans.
Usage example from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30)
Sources & notes
Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).
Sense 2
Meaning · English
To clown around; to have fun, often at the expense of others.
Register: informal
Sources & notes
Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).
Common questions
What does “muck up” mean?
To ruin unintentionally.
Is “muck up” formal or informal?
muck up is generally informal.