MeSH (Medical Subject Headings)
MeSH stands for Medical Subject Headings and is the vocabulary that helps to organize the citations found within the MEDLINE database (searchable in PubMed). MeSH can be used to assist users in finding the appropriate terms for their search.
MeSH reviewers read articles before they go into MEDLINE and assign appropriate subject headings to the article. These subject headings from a pre-set list (or vocabulary). MeSH applies one term to a collection of concepts - even if that exact term is not used in the article.
Try using the MeSH Browser to locate the best term to search in PubMed