Use a plural name for such enumeration types. The following code snippet is a good example of an enumeration that allows combining multiple options.

[Flags]
public enum SearchOptions
{
	CaseInsensitive = 0x01,
	WholeWordOnly = 0x02,
	AllDocuments = 0x04,
	Backwards = 0x08,
	AllowWildcards = 0x10
}