Using "Define" In Enhanced Subject Heading mode, researchers can also easily check their understanding of Subject Heading terms by clicking the Define button. Here are the results for the first term, Gram-Negative Aerobic Bacteria, in the Enhanced Subject Headings list of terms. This list was generated when we input "Gram negative" as the original search term. As you can see, there is much information provided here, including a History note about former headings used. Scroll down to move to the next slide.