Boolean is a set of language unique to a specific site which allows a user to search for certain keywords and key phrases. The biggest problem with Boolean is the fact that many sites have slightly different Boolean languages. This can be very frustrating for those who search. For example, Austlii has a different Boolean feature to HeinOnline
a certain datatype in computer science http://en.wikipedia.org/wiki/Boolean_datatype
a logical calculus of truth values or set http://en.wikipedia.org/wiki/Boolean_algebra_%28logic%29
a certain network consisting of a set of Boolean variables whose state is determined by other variables in the network http://en.wikipedia.org/wiki/Boolean_network
a certain algebraic structure in mathematics http://en.wikipedia.org/wiki/Boolean_algebra_%28structure%29
a function which determines Boolean values or operators http://en.wikipedia.org/wiki/Boolean_function