Bidi is short for "bi-directional" and means text containing text in both text directionalities, both right-to-left (RTL) and left-to-right (LTR). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text directionality in each row. See also the tag `right-to-left`
See also: right-to-left
Wikipedia: https://en.wikipedia.org/wiki/Bi-directional_text