Thumbird or Thumbbird: How To spell?
The word Thumbird is misspelled against Thumbbird, a noun meaning "The goldcrest."
Thumbbird has double "bb" is mispronounced as "b"Remember double 'BB' in between the strings Thum & ird which should not be misspelled with single 'B'
Wrong Spelling:  Thum-b-ird  Correct Spelling:  Thum-bb-ird 
Check more misspelled words of Thumbbird to spell it correct.