If I understand you correctly, you asked me to:
1) Open the iPad app "Notes"
2) type a word in a note
3) select that word I just typed (while the English keyboard remains active)
When I followed the above steps, the menu option "Define" does not even come up. My options are just "Cut, Copy, Paste, Suggest..."
After doing the above I realized you probably meant for me to create a note within iBooks. So, I did steps 1-3 in an iBook note and I got the same result.