Antonyms of adj specious

2 senses of specious

Sense 1
specious, spurious -- (plausible but false; "a specious claim"; "spurious inferences")

INDIRECT (VIA false) -> true -- (consistent with fact or reality; not false; "the story is true"; "it is undesirable to believe a proposition when there is no ground whatever for supposing it true"- B. Russell; "the true meaning of the statement")

Sense 2
gilded, meretricious, specious -- (based on pretense; deceptively pleasing; "the gilded and perfumed but inwardly rotten nobility"; "meretricious praise"; "a meretricious argument")

INDIRECT (VIA insincere) -> sincere -- (open and genuine; not deceitful; "he was a good man, decent and sincere"; "felt sincere regret that they were leaving"; "sincere friendship")

Similarity of adj specious

2 senses of specious

Sense 1
specious, spurious -- (plausible but false; "a specious claim"; "spurious inferences")
       => false (vs. true) -- (not in accordance with the fact or reality or actuality; "gave false testimony under oath"; "false tales of bravery")

Sense 2
gilded, meretricious, specious -- (based on pretense; deceptively pleasing; "the gilded and perfumed but inwardly rotten nobility"; "meretricious praise"; "a meretricious argument")
       => insincere (vs. sincere) -- (lacking sincerity; "a charming but thoroughly insincere woman"; "their praise was extravagant and insincere")