A steric or other interaction involving atoms or groups or both situated nearby in sequence along the chain. The interacting atoms or groups are typically separated by fewer than ten consecutive bonds in a chain. If no confusion can occur, the word 'intramolecular' may be omitted.
Source:
Purple Book, 1st ed., p. 48 (http://old.iupac.org/publications/books/author/metanomski.html)