Yes, slack is in the scrabble dictionary

...and is worth 13 points by itself.

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Slack Definition

noun

A cessation of movement in a current of air or water.
from The American Heritage Dictionary of the English Language, 4th Edition
A lack of tension; looseness.
from The American Heritage Dictionary of the English Language, 4th Edition
A loose part, as of a rope or sail.
from The American Heritage Dictionary of the English Language, 4th Edition
A mixture of coal fragments, coal dust, and dirt that remains after screening coal.
from The American Heritage Dictionary of the English Language, 4th Edition
A period of little activity; a lull.
from The American Heritage Dictionary of the English Language, 4th Edition

verb-intransitive

To be or become slack.
from The American Heritage Dictionary of the English Language, 4th Edition
To evade work; shirk.
from The American Heritage Dictionary of the English Language, 4th Edition

verb-transitive

To make slower or looser; slacken.
from The American Heritage Dictionary of the English Language, 4th Edition
To slake (lime).
from The American Heritage Dictionary of the English Language, 4th Edition

verb

To be or become slack.
from Free Scrabble Dictionary
To shirk or evade work or duty.
from Free Scrabble Dictionary
To be slack or negligent in performing or doing.
from Free Scrabble Dictionary
To release tension on.
from Free Scrabble Dictionary
To cause to abate.
from Free Scrabble Dictionary

idiom

Cut Slang To make an allowance for (someone), as in allowing more time to finish something.
from The American Heritage Dictionary of the English Language, 4th Edition

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Top Words by points

Points

calks

11

2 letter words with SLACK

Points

as

2

la

2

ka

6

al

2

3 letter words with SLACK

Points

ask

7

ska

7

sal

3

sac

5

las

3

lac

5

kas

7

ack

9

als

3

4 letter words with SLACK

Points

lack

10

lacs

6

cask

10

calk

10

sack

10

5 letter words with SLACK

Points

calks

11

lacks

11

slack

11

Found 21 words in 0.1402 seconds