|Noah Webster's Dictionary|
1. (v.) To become slack; to be made less tense, firm, or rigid; to decrease in tension; as, a wet cord slackens in dry weather.
2. (v.) To be remiss or backward; to be negligent.
3. (v.) To lose cohesion or solidity by a chemical combination with water; to slake; as, lime slacks.
4. (v.) To abate; to become less violent.
5. (v.) To lose rapidity; to become more slow; as, a current of water slackens.
6. (v.) To languish; to fail; to flag.
7. (v.) To end; to cease; to desist; to slake.
8. (v. t.) To render slack; to make less tense or firm; as, to slack a rope; to slacken a bandage.
9. (v. t.) To neglect; to be remiss in.
10. (v. t.) To deprive of cohesion by combining chemically with water; to slake; as, to slack lime.
11. (v. t.) To cause to become less eager; to repress; to make slow or less rapid; to retard; as, to slacken pursuit; to slacken industry.
12. (v. t.) To cause to become less intense; to mitigate; to abate; to ease.
13. (n.) A spongy, semivitrifled substance which miners or smelters mix with the ores of metals to prevent their fusion.
Slacken (1 Occurrence)
2 Kings 4:24 Then she saddled an ass, and said to her servant, Drive, and go forward; slacken me not the riding, except I bid thee. (See JPS ASV RSV)