Plausible but untrue

• Deceptively pleasing
• Deceptively convincing
• Superficially plausible
• Apparently right, but not really so
• Convincing at first, but flawed

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Specious \Spe"cious\, a. [L. speciosusgood-looking, beautiful, specious, fr. species look, show, appearance; cf. F. sp['e]coeux. See Species .] Presenting a pleasing appearance; pleasing in form or look; showy. Some [serpents] specious and beautiful ...

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
adjective EXAMPLES FROM OTHER ENTRIES ▪ specious logic EXAMPLES FROM CORPUS ▪ All that is needed is a positive approach and an end to the specious fear of isolation. ▪ Even so, the size-and-weight-of-head argument is a rather specious one. ▪ In the history ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
late 14c., "pleasing to the sight, fair," from Latin speciosus "good-looking, beautiful, fair," also "showy, pretended, plausible, specious," from species "appearance, form, figure, beauty" (see species ). Meaning "seemingly desirable, reasonable or probable, ...

Wikipedia Word definitions in Wikipedia