Real Dictionary

asterisk
countable noun: An asterisk is the sign *. It is used especially to indicate that there is further information about something in another part of the text.

asterisk in American English
a starlike sign (*) used in printing to indicate footnote references, omissions, etc.
to mark with this sign
noun: a small starlike symbol (*), used in writing and printing as a reference mark or to indicate omission, doubtful matter, etc

asterisk in British English
noun: a star-shaped character (*) used in printing or writing to indicate a cross-reference to a footnote, an omission, etc
verb: to mark with an asterisk