An abbreviation of 'asterisk' (the symbol '*'); a shortened, often informal term used in documents or speech.
注意事項はアステリで示しておいたから、あとで注釈を付けてね。
I've marked the notes with an asterisk, so please add the annotations later.
表の必須欄にアステリを付けておいてください。
Please mark the required columns in the table with an asterisk.