You placed the word ALPHAJAX on a board.
This achievement requires that you make the word "ALPHAJAX" on the board. Use techniques found in "Anodyne Supremacy" to get all of the tiles you need into your main account's rack. The important thing to note is that the entire word does not need to be built in the same turn. Build your board favorably so you can start piecing together the word. I personally recommend building "AL", then add P-H-A to make "ALPHA," then add J-A-X to make the complete word. The secondary account can lay down any of the letters, except the J-A-X to complete the word. With focused effort on this achievement only, it should take less 20 minutes or so, depending how lucky you are with letters (especially the J or X, which there is only one of each in the game).