Antonym: quicken. Similar words: blacken, sicken, chicken, thicken, quicken, stricken, chicken out, packet. Meaning: ['slækən] 
v. 1. become slow or slower 2. make less active or fast 3. become looser or slack 4. make slack as by lessening tension or firmness.
v. 1. become slow or slower 2. make less active or fast 3. become looser or slack 4. make slack as by lessening tension or firmness. 
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1. Slacken your legs and slowly lie back.
2. Simon allowed his pace to slacken.
3. Growth in the economy was beginning to slacken off.
4. We're on the last lap, so don't slacken!
5. Nothing could make us slacken off.
6. Inflationary pressures continued to slacken last month.
7. Slacken the reins or you'll hurt the horse's mouth.
8. After hours of digging, we began to slacken up a little.
9. The Conservative government will not slacken the pace of radical reform.
10. Most people slacken off/up at the end of a day's work.
11. The management expects demand to slacken in the New Year.
12. Slacken off the ropes.
13. The pace did not slacken in the fifth.
14. Don't allow the reins to slacken, keep them taut.
15. But it should slacken when the leash is held normally.
16. In the heat of the moment, he might slacken his moral principles.
17. Slacken the chocolate mixture with one-third of them then fold in the rest.
18. Slacken off the line, and pull the fishing rod towards you.
19. If this is the case, slacken the rod by small increments until the buzz goes.
20. I tried to slacken pace but the slowest I went seemed to be faster than I had ever run before.
21. But soon he had to slacken, for Nora made no attempt to match his pace.
22. She would not even slacken speed as she raced through the far-ranging Jovian satellite system.
23. We've been really busy,(sentencedict.com) but things are starting to slacken off now.
24. Better have no war for a thousand days than slacken your vigilance for one day.
25. I was warned again and again by friendly police officers of some rank to slacken the pace: and I refused.
26. Only after the second death on that mild, sunny Saturday eight days ago did the pace of planes and people slacken.
27. Workers can be trained to do other tasks when sales slacken.
28. A good tree tie will be adjustable and easy to slacken off.
29. The surge of profits fueling the stock market boom refuses to slacken.
30. The pilots cautiously relaxed their grip and let their muscles slacken.
More similar words: blacken, sicken, chicken, thicken, quicken, stricken, chicken out, packet, packed, jacket, lack, knacker, bracket, cracked, black, quackery, black out, lacking, linebacker, black hand, for lack of, blackmail, black list, blacklist, blackface, in the black, black sheep, blackberry, black horse, lacklustre.