Synonyms for Downright:

adj.

absolute (adjective)
crashing, unqualified.
artless (adjective)
open, frank, trusting, sincere, artless, ingenuous, undeceitful, blunt, undisguised, undeceptive, Plain-spoken, direct, outgoing, genuine, undeceiving, candid, Unartful, naive, straightforward, uncalculating, unsophisticated, callow, unrestrained, overt, plain, unaffected, natural, honest, un-artificial, broad, Unbeguiling.
complete (adjective)
out-and-out.
direct (adjective)
undisguised.
perfect (adjective)
perfect.
plainspoken (adjective)
plainspoken, Plain-spoken, man-to-man.
positive (adjective)
positive.
thorough, absolute (adjective)
complete, out-and-out, open, sincere, unqualified, straight, outright, plain, blunt, unmitigated, total, utter, unequivocal, undisguised, damned, flat, clear, thoroughgoing, straightforward, positive, honest.

adv.

entirely (adverb)
completely.

n.

resounding, good, sound, in depth. outright, big, limited, thoroughly, crashing, unmitigated, dead, fully, unrelieved, utter, thorough, thoroughgoing, unbounded, blooming, perfect, all-out, unlimited, flat, purely, flat out, unequivocal, well, positive, consummate, total, pure, arrant, really, totally, damned, unreserved, unqualified. plainspoken, forthright, man-to-man, show, straight-out, straight, straight-from-the-shoulder, clear, straight-shooting. downright (noun)
honorable, out-and-out, complete, rank, honest, right-down, sheer, absolute.
frank (noun)
abrupt.
thorough (noun)
thoroughgoing, total, utter.
thoroughly (noun)
entirely, absolutely, utterly, completely.

Other synonyms:

man-to-man, crashing, unrelieved, straight-from-the-shoulder, arrant, straight-out, plainspoken. outright, thoroughgoing, straight-shooting, abrupt, forthright. flat out, consummate, unlimited, unmitigated, all-out, unbounded, pure. blooming, thorough, unequivocal. damned, straight, unreserved. positive. complete, dead, perfect. flat. Other relevant words:
positive, clear, resounding, thoroughgoing, man-to-man, arrant, outright, abrupt, rank, crashing, totally, in depth, utter, perfect, forthright, complete, utterly, thoroughly, out-and-out, unbounded, honorable, flat, absolute, all-out, flat out, pure, sound, blooming, absolutely, plainspoken, unreserved, consummate, fully, straight-out, show, entirely, straight, good, well, unqualified, unlimited, straight-from-the-shoulder, dead, completely, unrelieved, unmitigated, thorough, really, purely, unequivocal, right-down, damned, limited, big, total, sheer, straight-shooting.

Usage examples for downright

  1. One day he pushed my patience beyond all limit, and I grew downright angry with him. – That Boy Of Norcott's by Charles James Lever
  2. There is a sort of defiance of him in stopping; there is a downright concession to him in going away." – Basil by Wilkie Collins
  3. All I did was, I hesitated, and cried, and didn't say 'no, ' downright like a fool. – Put Yourself in His Place by Charles Reade