How to highlight all occurrences of a selected word in VIM?

Question

In Normal mode:

:set hlsearch

Then search for a pattern with the command / in Normal mode, or <Ctrl>o followed by / in Insert mode. * in Normal mode will search for the next occurrence of the word under the cursor. The hlsearch option will highlight all of them if set. # will search for the previous occurrence of the word.

To remove the highlight of the previous search:

:nohlsearch

You might wish to map :nohlsearch<CR> to some convenient key.

The * key will highlight all occurrences of the word that is under the cursor.

I know than it's a really old question, but if someone is interested in this feature, can check this code http://vim.wikia.com/wiki/Auto_highlight_current_word_when_idle

" Highlight all instances of word under cursor, when idle.
" Useful when studying strange source code.
" Type z/ to toggle highlighting on/off.
nnoremap z/ :if AutoHighlightToggle()<Bar>set hls<Bar>endif<CR>
function! AutoHighlightToggle()
   let @/ = ''
   if exists('#auto_highlight')
     au! auto_highlight
     augroup! auto_highlight
     setl updatetime=4000
     echo 'Highlight current word: off'
     return 0
  else
    augroup auto_highlight
    au!
    au CursorHold * let @/ = '\V\<'.escape(expand('<cword>'), '\').'\>'
    augroup end
    setl updatetime=500
    echo 'Highlight current word: ON'
  return 1
 endif
endfunction

the simplest way, type in normal mode *

I also have these mappings to enable and disable

"highligh search enabled by default
set hlsearch
"now you can toggle it
nnoremap <S-F11> <ESC>:set hls! hls?<cr>
inoremap <S-F11> <C-o>:set hls! hls?<cr>
vnoremap <S-F11> <ESC>:set hls! hls?<cr> <bar> gv

Select word by clickin on it

set mouse=a     "Enables mouse click
nnoremap <silent> <2-LeftMouse> :let @/='\V\<'.escape(expand('<cword>'), '\').'\>'<cr>:set hls<cr>

Bonus: CountWordFunction

fun! CountWordFunction()
    try
        let l:win_view = winsaveview()
        let l:old_query = getreg('/')
        let var = expand("<cword>")
        exec "%s/" . var . "//gn"
    finally
        call winrestview(l:win_view)
        call setreg('/', l:old_query)
    endtry
endfun
" Bellow we set a command "CountWord" and a mapping to count word
" change as you like it
command! -nargs=0 CountWord :call CountWordFunction()
nnoremap <f3> :CountWord<CR>

Selecting word with mouse and counting occurrences at once: OBS: Notice that in this version we have "CountWord" command at the end

nnoremap <silent> <2-LeftMouse> :let @/='\V\<'.escape(expand('<cword>'), '\').'\>'<cr>:set hls<cr>:CountWord<cr>

Search based solutions (*, /...) move cursor, which may be unfortunate.

An alternative is to use enhanced mark.vim plugin, then complete your .vimrc to let double-click trigger highlighting (I don't know how a keyboard selection may trigger a command) :

"Use Mark plugin to highlight selected word  
map <2-leftmouse> \m   

It allows multiple highlightings, persistence, etc.

To remove highlighting, either :

• Double click again
• :Mark (switch off until next selection)
• :MarkClear

First (or in your .vimrc):

:set hlsearch

Then position your cursor over the word you want highlighted, and hit *.

hlsearch means highlight all occurrences of the current search, and * means search for the word under the cursor.