to become slack; to be made less tense, firm, or rigid; to decrease in tension; as, a wet cord slackens in dry weather.-to be remiss or backward; to be negligent.-to lose cohesion or solidity by a chemical combination with water; to slake; as, lime slacks.-to abate; to become less violent.-to lose rapidity; to become more slow; as, a current of water slackens.-to languish; to fail; to flag.-to end; to cease; to desist; to slake.-to render slack; to make less tense or firm; as, to slack a rope; to slacken a bandage.-to neglect; to be remiss in.-to deprive of cohesion by combining chemically with water; to slake; as, to slack lime.-to cause to become less eager; to repress; to make slow or less rapid; to retard; as, to slacken pursuit; to slacken industry.-to cause to become less intense; to mitigate; to abate; to ease.-a spongy, semivitrifled substance which miners or smelters mix with the ores of metals to prevent their fusion.