From Proto-Slavic *slovo ("word, speech"), related to *sluti ("to be known, to be called") and *slava ("glory, fame"). Cognate with Old Church Slavonic слово, and distantly related to English "listen" via Proto-Indo-European *ḱlew- ("to hear, to be famous").

In Russian culture, слово carries considerable weight beyond its literal meaning. The phrase держать слово (to keep one's word) is a mark of personal honour. Notably, one of the oldest East Slavic literary works is called «Слово о полку Игореве» ("The Tale of Igor's Campaign", ~12th century), cementing слово as a near-sacred concept tied to narrative and oral tradition. Also watch out: the English "slovo" is occasionally borrowed into South African slang (from Afrikaans, via Zulu), but is unrelated.