clump up
B2 neutral inseparable both
In simple words
When things stick together and form a big group or lump instead of staying separate.
Literal meaning: To form ('up') into a clump ('clump').
Meanings
1 B2 neutral
Of physical matter: to stick together and form a dense lump or mass.
"The mascara had clumped up because she forgot to close the tube properly."
Grammar: inseparable
2 B2 informal
Of people or animals: to gather into a tight group or cluster.
"The tourists clumped up at the entrance, blocking the doorway for everyone else."
Grammar: inseparable
Usage notes
Used in both physical contexts (soil, hair, powder) and biological or social contexts (cells, animals, people). The 'up' particle suggests completeness — becoming one solid mass. Common in scientific and everyday contexts.
Commonly used with
hair soil cells crowd powder particles
Forms
Base
clump up
I/you/we/they
3rd person
clumps up
he/she/it
Past simple
clumped up
yesterday
Past participle
clumped up
have + pp
-ing form
clumping up
continuous
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