slack up
C1 informal inseparable both
In simple words
To slow down or stop pulling so hard on something.
Literal meaning: To bring something up to a slack (loose) state — to release tension.
Meanings
1 C1 informal
To reduce speed or slow down.
"The driver slacked up as the car approached the junction."
Grammar: inseparable
2 C1 neutral
To release tension on a rope or line (nautical use).
"Slack up on the bowline before we try to move the sail."
Grammar: inseparable
Usage notes
Chiefly American dialectal or nautical English. In sailing, it means to loosen a rope. Rarely used in modern standard English; learners should prefer 'ease up' or 'let up'.
Commonly used with
rope pace tension speed pressure
Forms
Base
slack up
I/you/we/they
3rd person
slacks up
he/she/it
Past simple
slacked up
yesterday
Past participle
slacked up
have + pp
-ing form
slacking up
continuous
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