Truncation, or finding all terms that begin with a given string of text, is generally not a recommended search technique for PubMed. Truncation bypasses Automatic Term Mapping and automatic explosion. Also, in such a large database, variations of a text string can become overwhelming and unmanageable. Especially when multiple terms are truncated, PubMed may even time out and fail in an attempt to run the search. However, there are times when limited use of truncation can be useful.
The PubMed truncation symbol is the asterisk (*), sometimes referred to as a "wildcard."
For example, let's say you are trying to search all terms that have the root, mimic. If you search mimic* PubMed will retrieve words such as mimic, mimics, mimicing, etc.
PubMed supports only end-truncation. There is no single character symbol.
PubMed restricts retrieval to the first 600 variations of the truncated term. When this occurs, PubMed will display a warning message.