How much do the lexicons of Czech and Slovak differ, according to on study?
One study showed that Czech and Slovak lexicons differed by 80 percent, but this high percentage was found to stem primarily from differing orthographies and slight inconsistencies in morphological formation; Slovak morphology is more regular (when changing from the nominative to the locative case, Praha becomes Praze in Czech and Prahe in Slovak). The two lexicons are generally considered similar, with most differences in colloquial vocabulary and some scientific terminology. Slovak has slightly more borrowed words than Czech.
The English word Slav could be derived from the Middle English word sclave, which was borrowed from Medieval Latin sclavus or slavus, itself a borrowing and Byzantine Greek σκλάβος sklábos "slave," which was in turn apparently derived from a misunderstanding of the Slavic autonym (denoting a speaker of their own languages). The Byzantine term Sklavinoi was loaned into Arabic as Saqaliba صقالبة (sing. Saqlabi صقلبي) by medieval Arab historiographers. However, the origin of this word is disputed.