Once in a while a word comes to have opposite meanings. The adjective especioso/specious is such a word. Compare the pairs of definitions in the 1913 Webster’s Unabridged Dictionary and the Diccionario de la Real Academia Española:
1. Apparently right; superficially fair, just, or correct, but not so in reality; appearing well at first view; plausible; as, specious reasoning; a specious argument.
2. Presenting a pleasing appearance; pleasing in form or look; showy.
1. Hermoso, precioso, perfecto.
2. Aparente, engañoso.
Here are the main translations that Lewis and Short’s A Latin Dictionary gave for speciōsus:
Good-looking, showy, handsome, beautiful, splendid, brilliant.
In a secondary definition of the Latin adjective we see the genesis, even in Roman times, of the negative sense:
Well-sounding, plausible, specious.
In other words, something especioso/specious looks pleasant enough and is therefore plausible (i.e. applaudable), but someone has created the attractive appearance as a way to hide the truth.
The negative sense of specious has driven out the ‘showy’ one in modern English, but apparently not in Spanish, where the DRAE gives the positive definition first. And botanists have preserved the positive sense in species names like Ungnadia speciosa and Oenothera speciosa.
As for Latin speciōsus itself, that adjective was based on the root found in the verb specere ‘to look at,’ with past participle spectus, about which much more could be said.
© 2016 Steven Schwartzman