Definition of gullibility in US English:

gullibility

noun

  • A tendency to be easily persuaded that something is real or true; credulity.

    ‘you can never underestimate the gullibility of people’

Origin

Late18th century: alteration of the obsolete word cullability (in the same meaning), after gull.

Pronunciation

gullibility

/ˌɡələˈbilədē/