before vowels log-, word-forming element meaning "speech, word," also "reason," from Greek logos "word, discourse; reason," from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')."
Entries linking to logo-
*leg- 1
Proto-Indo-European root meaning "to collect, gather," with derivatives meaning "to speak" on the notion of "to gather words, to pick out words."