set path+=/path/to/your/rails-application/app/** set path+=/path/to/your/rails-application/lib/** set suffixesadd=.rb set includeexpr+=substitute(v:fname,'s$','','g') "" or you can add substitution pattern s/ies$/y/g, s/ves$/f/g like this: "" set includeexpr+=substitute(substitute(substitute(v:fname,'s$','','g'),'ie$','y','g'),'ve$','f','g')