Why isn't there a meta keywords field?
We don't have a 'Keywords' field for articles like you might typically see in other content management systems.
This is because it's widely regarded that it has no impact on search engines.
In 2009, Google announced officially "Google does not use the keywords meta tag in web ranking". Matt Cutts explained it in a video.
This article from Yoast covers the reasoning for not including a Keywords field particularly well.
We recommend focussing effort on page titles, meta description (or 'Abstract' as it is referred to in our news article editor), images and the content of articles themselves.