Synonyms for Straightforward:

adj.

all (adjective)
straight, square.
artless (adjective)
candid, open, plain, artless, Unbeguiling, outgoing, frank, blunt, genuine, unsophisticated, unadorned, undeceptive, callow, downright, Plain-spoken, unrestrained, ingenuous, Unartful, undeceitful, un-artificial, uncalculating, unaffected, natural, sincere, naive, trusting, direct, undeceiving, honest, undisguised, overt, broad.
direct (adjective)
through.
honest (adjective)
direct, plain, forthright, sincere, frank, aboveboard, genuine, undisguised, unequivocal, honorable, straight, upstanding, truthful, candid, outspoken, open.
intelligible (adjective)
consistent, coherent, perspicuous, legible, understandable, comprehensible, clear, crisp, self-explanatory, decipherable, lucid, direct, plain, intelligible.
plainspoken (adjective)
plainspoken, man-to-man, Plain-spoken.
reputable (adjective)
honorable.
simple (adjective)
artless.
simple, easy (adjective)
clear, unambiguous, through.
square (adjective)
square.
succinct (adjective)
clear, prosaic, candid, intelligible, honest, stark, casual, direct, bald, unadorned, ordinary, unpoetical, simple, Plain-spoken, blunt, unpretentious, uncluttered, informal, folksy, frank, outspoken.
truthful (adjective)
ethical, earnest, trustworthy, frank, factual, candid, sincere, truthful, honest, honorable.
veracious (adjective)
undeceptive.

n.

fine, decent, irreproachable, principled, upstanding, good. easy, through, make sense. straight-out, straight-from-the-shoulder, forthright, show, man-to-man, plainspoken, straight-shooting. straightforward (noun)
unambiguous, unequivocal, aboveboard, straight, direct, square, univocal.

Other synonyms:

man-to-man, straight-out, plainspoken, straight-from-the-shoulder. easy, straight-shooting, forthright. honorable
upstanding.

Usage examples for straightforward

  1. The quiet, straightforward way he said this made a good impression. – The Bridal March; One Day by Bjørnstjerne Bjørnson
  2. Peter had not ceased to be straightforward – The Honorable Peter Stirling and What People Thought of Him by Paul Leicester Ford
  3. " From a medical point of view it is all straightforward – The Grell Mystery by Frank Froest