title: Regular expression to match a line that doesn't contain a word
body: <p>I know it's possible to match a word and then reverse the matches using other tools (e.g. <code>grep -v</code>). However, is it possible to match lines that do not contain a specific word, e.g. <code>hede</code>, using a regular expression?</p>
  <h5>Input:</h5>
  <pre><code>hoho
  hihi
  haha
  hede
  </code></pre>
  <h5>Code:</h5>
  <pre><code>grep &quot;&lt;Regex for 'doesn't contain hede'&gt;&quot; input
  </code></pre>
  <h5>Desired output:</h5>
  <pre><code>hoho
  hihi
  haha
  </code></pre>