<form method="post">
  <textarea name="your-message" cols="40" rows="10" class="wpcf7-form-control wpcf7-textarea"></textarea><br>
  <input type="submit" value="Send your message" class="wpcf7-form-control wpcf7-submit">
</form>



//jQuery For Prevent Submission
jQuery(".wpcf7-submit").click(function ($) {
        var words = ["Title Tag", "SEO", "Marketing", "Website Speed Development", "Traffic", "1st page", "Heading Tags","Ranking","Publisher","Speed","Development"]; // Words For preventing Submission
  var i = 0;
        for (i = 0; i &amp;amp;amp;amp;lt; words.length; i++) { if (jQuery(".wpcf7-textarea").val().indexOf(words[i]) &amp;amp;amp;amp;gt;= 0) {
                alert('Your Message Contains Bad Words, Please Remove Them Before Proceeding');
                return false;
            }
        }
    });

Refer Below link for Example:

https://codepen.io/parths267/pen/dmvqWE

 

 

 

JS/jQuery