<input type="checkbox"/> <label style="display: inline-block; width: 60px; overflow: hidden">Sample text sample text</label>

HTML:
<input type="checkbox"/>
    <label>Pretty awesome label to describe the uber cool checkbox. </label>

CSS:
    label {
      text-overflow: ellipsis;
      display: inline-block;
      overflow: hidden;
      width: 300px;
      white-space: nowrap;
      vertical-align: middle;
    }