The Slavic autonym *Slověninъ is usually considered (e.g. by Roman Jakobson) a derivation from slovo "word", originally denoting "people who speak (the same language)," i.e. people who understand each other, in contrast to the Slavic word denoting "foreign people" – němci, meaning "mumbling, murmuring people" (from Slavic *němъ – "mumbling, mute").
Who considered *Slověninъ do be a derivation from slovo?
Roman Jakobson