Slack \Slack\, Slacken \Slack"en\, v. t.

1. To render slack; to make less tense or firm; as, to slack a rope; to slacken a bandage. --Wycklif (Acts xxvii. 40)

2. To neglect; to be remiss in. [Obs.]

--Shak.

Slack not the pressage. --Dryden.

3. To deprive of cohesion by combining chemically with water; to slake; as, to slack lime.

4. To cause to become less eager; to repress; to make slow or less rapid; to retard; as, to slacken pursuit; to slacken industry. ``Rancor for to slack.'' --Chaucer.

I should be grieved, young prince, to think my presence Unbent your thoughts, and slackened 'em to arms. --Addison.

In this business of growing rich, poor men should slack their pace. --South.

With such delay Well plased, they slack their course. --Milton.

5. To cause to become less intense; to mitigate; to abate; to ease.

To respite, or deceive, or slack thy pain Of this ill mansion. --Milton.

Air-slacked lime, lime slacked by exposure to the air, in consequence of the absorption of carton dioxide and water, by which it is converted into carbonate of lime and hydrate of lime.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Slack \Slack\, Slacken \Slack"en\, v. i. [imp. & p. p. Slacked, Slackened; p. pr. & vb. n. Slacking, Slackening.]

[See Slack, a.]

1. To become slack; to be made less tense, firm, or rigid; to decrease in tension; as, a wet cord slackens in dry weather.

2. To be remiss or backward; to be negligent.

3. To lose cohesion or solidity by a chemical combination with water; to slake; as, lime slacks.

4. To abate; to become less violent.

Whence these raging fires Will slacken, if his breath stir not their flames. --Milton.

5. To lose rapidity; to become more slow; as, a current of water slackens.

6. To languish; to fail; to flag.

7. To end; to cease; to desist; to slake. [Obs.]

That through your death your lineage should slack. --Chaucer.

They will not of that firste purpose slack. --Chaucer.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Slacken \Slack"en\, n. (Metal.) A spongy, semivitrifled substance which miners or smelters mix with the ores of metals to prevent their fusion. [Written also slakin.]

Source: Webster's Revised Unabridged Dictionary (1913)