Decistere is not a commonly used word and therefore is not found in most dictionaries. However, considering its roots, it is likely that this word is spelled as "deci" followed by "stere". The prefix "deci" means one-tenth, and "stere" is a unit of measurement for volume, often used in the context of gases such as air. The word would be pronounced /ˈdɛsɪstɪər/. Without context, it is difficult to determine the precise meaning intended by this word.