You can't do that directly; only (buffer-local) options can be set in modeline.
option 1
If this additional keyword is not special to a single file, but applies to a wide range of files, I'd define a custom filetype (e.g. mybash
), and have that additional keyword added in ~/.vim/syntax/mybash.vim
:
" mybash is a kind of shell syntax
runtime! syntax/sh.vim syntax/sh/*.vim
" Add keyword.
syntax keyword mybashKeyword verbose
To use that custom syntax, you either augment the default filetype detection rules, or include ft=mybash
in the modeline.
option 2
If this is just a minor tweak for one or few files, I'd use a local vimrc plugin to add the keyword.
There are several such plugins on vim.org; I can recommend the localrc plugin, which even allows local filetype-specific configuration.