put (one) down
1. To insult, mock, belittle, or disparage one. The boss is always putting me down in front of everyone in the office. It's really making my life miserable. Tommy, don't put your brother down like that—if you don't have anything nice to say, don't say anything.
2. To kill one. The marshal told the fugitive that he would put him down if he reached for his gun.
3. To euthanize an animal. We knew our poor dog was suffering, so we decided it was time to put her down.