I have discovered that it is possible in insert mode to execute a single command and return to insert mode by using Ctrl-O.
What about the possibility to insert a single word while in normal mode ?
I could, of course, switch to insert mode, write the word, escape and go back to normal mode.
But I wondered if it was possible to map a sequence (e.g. Ctrl-K) allowing without leaving normal mode to quickly add a single word at the cursor position ?
I tried mapping a function with a prompt (cf. question 11567596 - Ingo Karkat's answer - and Wikia tip 1616) but failed : the word was appended at the end of the line...