Add word under cursor to search pattern

Question

Using * when the cursor is on a word theWord, vim directly jumps to the next appearance of exactly that word, i.e. performes /\\

Answer 1

Try

:nnoremap  + :let @/ .= '\\|\<'.expand('').'\>'n

That will append the word under the cursor to the search register when '+' is hit, and jump to the next occurrence of any searched pattern.

If you wish to extend it to the visual mode, (as it could be done to n_star), you have

:vnoremap  + :let @/ .= '\\|'.escape(lh#visual#selection(), '/\^$*.[~')n

With lh#visual#selection() to fetch the current selection, and escape() to neutralize some active characters in regexes. v_CTRL-\_CTRL-N being a safe and silent escape sequence.