credulous

Etymology

Originated in 1576, borrowed from Latin crēdulus (“that easily believes a thing, credulous”), from crēdō (“to believe”).

adj

1. Excessively ready to believe things; gullible.
   […]purſued his vnneighbourly purpoſe in ſuch ſort: that hee being the ſtronger perſwader, and ſhe (belike) too credulous in beleeuing or elſe ouer-feeble in reſiſting, from priuate imparlance, they fell to action; and continued their cloſe fight a long while together, vnſeene and vvithout ſuſpition, no doubt to their equall ioy and contentment. 1620, Giovanni Bocaccio, translated by John Florio, The Decameron, Containing an Hundred Pleaſant Nouels: Wittily Diſcourſed, Betweene Seuen Honourable Ladies, and Three Noble Gentlemen, Isaac Iaggard, Nouell 8, The Eighth Day
2. Believed too readily.
   The powerful mind of Aristotle, which led him to reject with disdain the credulous tales and fabulous stories of the age, can nowhere be traced in the writings of Pliny, whose works, on the contrary, abound in fables and in prodigies, at once manifesting that weakness of mind inseparable from credulity, or that disinclination to investigate truth, which is the sure mark of a secondary order of intellect. 1834, William Swainson, A Preliminary Discourse on the Study of Natural History (Cabinet Cyclopedia), pages 8–9
   The media (and politicians) are replete with credulous stories about machine learning and AI, but these stories are often based on commercial claims. 2020, David Spiegelhalter, “Should We Trust Algorithms?”, in Harvard Data Science Review, volume 2, number 1, →DOI, page 2