Antonym: soften. Similar words: garden, warden, ardent, gardener, ardently, gardening, herb garden, hard-earned. Meaning: ['hɑrdn /'hɑː-] 
v. 1. become hard or harder 2. make hard or harder 3. harden by reheating and cooling in oil 4. make fit 5. cause to accept or become hardened to; habituate.
v. 1. become hard or harder 2. make hard or harder 3. harden by reheating and cooling in oil 4. make fit 5. cause to accept or become hardened to; habituate. 
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(1) Sorrow and trouble either soften the heart or harden it. 
(2) Hot steel is quenched to harden it.
(3) The varnish takes a few hours to harden.
(4) The varnish takes a few minutes to harden.
(5) I need to harden myself against disappointment.
(6) Property prices are just beginning to harden again.
(7) In this job you have to harden your heart to pain and suffering.
(8) He often went to the gym to harden his muscles.
(9) Their action can only serve to harden the attitude of landowners.
(10) You've just got to harden your heart and tell him to leave.
(11) The glue needs about 24 hours to harden.
(12) Hardships can harden even the best person. Amy Tan
(13) He watched the men harden to the mechanical slaughter.
(14) But difficulties did not harden his heart.
(15) And then Nancy will harden her heart against him.
(16) I try to harden myself(sentencedict.com/harden.html), push the guilt away.
(17) Harden the chocolates by putting them in the fridge.
(18) The clay needs to harden before it can be painted.
(19) At Somerset, the post went to Richard harden. it was a popular one for a talented and local boy.
(20) Evidence seemed to harden somewhat when a Glamorgan farmer went to the aid of a ditched van one dark night.
(21) It will take about 24 hours for the glue to harden.
(22) Give the cardboard two or three coats of varnish to harden it.
(23) The bitter split which has developed within Solidarity is likely to harden further into separation.
(24) You may leave the jelly in a cool place to harden it.
(25) Test to see if the finish is tacky, and if it is, leave it to harden.
(26) If this is done in hardness of spirit, it tends to harden attitudes and drive people away for the Lord.
(27) Feeling the solid flesh beneath his fingers he felt himself harden, completely unaware that Michael was planning his demise.
(28) He gave up trying to understand it and vowed to harden himself more.
(29) Any two solids can therefore be glued together if we can find a liquid which will wet them both and then harden.
(30) Kiki thought about these things as she was lying naked in her bed wishing the fudge would harden.
More similar words: garden, warden, ardent, gardener, ardently, gardening, herb garden, hard-earned, garden rake, victory garden, botanical garden, landscape gardener, burden, larder, warder, unburden, guarded, bearded, boarder, disburden, retarded, overburden, burdensome, car dealer, discarded, unguarded, hard, avant-garde, avantgarde, shard.