On behalf of Oxford University Press, Oxford Dictionaries can confirm that the word 'gullo' does not currently qualify for inclusion in any Oxford Dictionary.
"Oxford University Press has one of the largest and most wide-ranging language research programmes in the world, and it publishes an extensive range of dictionaries. New words, senses, and phrases are added to dictionaries such as OxfordDictionaries.com and the Oxford English Dictionary once editors have gathered enough independent evidence from a range of sources to be confident that they have widespread currency in English over time. At present, 'gullo' does not meet these entry criteria. To discover how we find out about new words, and how we decide whether or not they should be added to one of our dictionaries, watch our animated video here "
Ameena Saiyid OBE
Managing Director
Oxford University Press