Some languages have symbols with zero display's width or/and vowels/signs which

Some languages have symbols with zero display's width or/and vowels/signs which
are not an alphabetic character although they are not word-breakers too.
So, treat them as part of word.

Per off-list discussion with Dibyendra Hyoju <dibyendra@gmail.com> and
and Bal Krishna Bal <balkrishna7bal@gmail.com> about Nepali language and
Devanagari alphabet.