What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately, we currently do not have an option to do that.
However, it is possible to do this via your jotform's source code. Please see this thread here http://www.jotform.com/answers/355370-How-to-stop-form-submitting-when-enter-is-pressed for a workaround provided by one of our supporters who explains how to do that.
Or you could also add a test code field so that accidental submissions using the "Enter" key would be avoided.
Or you could also add the Captcha field and make it required so that accidental submissions can be avoided.
I hope this helps.