\ba Unicode word boundary
\w*?a Unicode word character, repeated any number of times
a-zone character from a (9710) to z (12210) (case insensitive)
\1the text saved by group 1
\1the text saved by group 1
\w*a Unicode word character, repeated any number of times
\ba Unicode word boundary
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string
i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters