(?<=\s)\w+(?=\s)

^ see solution above

// find all stand-alone words: a stand-alone word contains only a-fA-F0-9 and _
there once was a typo left out of the refifo, and it was made of CHEE_SE this wasn't the way, as they say, that it was supposed to be.  All the shoes in all the shoes boxes had 88or 99 laces.  THe_y were not grey or ugly in any way but that is for you and not me.  A hiccup for the typo was hiding in plain sighto brining much glee.  this is a w0R_____D and Th4t is a wurd and no let;s see% wat i s n t a word, how about &This or HowAbout_that? And that is the story about typo.

// your solution may use up to 13 characters in the regex
// hint: in this test "glee." does not match because glee is not stand-alone