The basic definition from Google for thin content (in the context of violating Google quality guidelines and incurring a penalty) involves having little or no original content:
“One of the most important steps in improving your site’s ranking in Google search results is to ensure that it contains plenty of rich information that includes relevant keywords, used appropriately, that indicate the subject matter of your content.
For many ecommerce sites, sites with hundreds of mostly duplicated pages, and others, fixing thin content may seem like an impossible goal. But thin content is the opposite of the unique, relevant quality content that search engines want to show on results pages. Thin content can hurt a website’s SEO and revenue.
Panda has been part of Google's algorithm since February 2011. The Google Panda update aims to prevent poor quality content from making it to the top of search results. If Google thinks your website provides low-quality content, you may get hit with a Panda penalty, and it will be harder for your website to rank.
To improve this some important things you have to remember while writing content are: Before writing content, ask normal user or also keep in mind what they think about product or website.
If you are still working with just keywords, then it will be worst thing for your content. You need to include all the related terms on a topic not just keywords.