Synonyms for Ingenuous:

adj.

all (adjective)
innocent.
artless (adjective)
frank, broad, naive, undisguised, Plain-spoken, undeceiving, trusting, genuine, plain, unsophisticated, outgoing, true, undeceitful, overt, natural, sincere, Unartful, undeceptive, unrestrained, downright, candid, unaffected, straightforward, open, straight, artless, Unbeguiling, blunt, uncalculating, honest, direct, un-artificial, callow.
candid (adjective)
blunt, forthright.
frank (adjective)
downright, Plain-spoken.
green (adjective)
callow, untrained.
honest (adjective)
authentic, veracious.
ingenuous (adjective)
innocent, open, plain, sincere, trusting, unstudied, straightforward, Unartful, unsophisticated, naive, unaffected, undisguised, artless, candid, natural, frank.
innocent (adjective)
unworldly, un-artificial, inexperienced.
plainspoken (adjective)
Plain-spoken, man-to-man, plainspoken.
simple (adjective)
artless.
veracious (adjective)
authentic, correct, genuine, veracious, factual, honest, true, accurate.

n.

unskilled, uninitiated, illiterate, be unused to (doing) something, uneducated, inexperienced, untrained, unqualified, untried. unstudied, unworldly. straight, plainspoken, clear, straight-shooting, man-to-man, forthright, straight-out, show, straight-from-the-shoulder. ingenuous (noun)
candid, artless, innocent, open, undistorted.

Other synonyms:

plainspoken, straight-out, straight-from-the-shoulder, man-to-man. unstudied, straight-shooting, forthright. straight, unworldly. Other relevant words:
innocent, clear, unworldly, inexperienced, straight, show, uninitiated, illiterate, forthright, undistorted, untrained, man-to-man, unqualified, straight-shooting, unskilled, plainspoken, straight-from-the-shoulder, untried, unstudied, uneducated, straight-out.

Usage examples for ingenuous

  1. How ingenuous I have been not to perceive it before!" – The Lion's Share by E. Arnold Bennett
  2. He had never asked her to write, and her note had seemed to him a trifle too ingenuous – Mysterious Mr. Sabin by E. Phillips Oppenheim