As far as the Slavs' own self-designation goes, its meaning is, understandably, better than “slave” it comes from the Indo-European root *kleu-, whose basic meaning is “to hear” and occurs in many derivatives meaning “renown, fame.”
Even to read the dictionary we need to pay careful attention. In my message I said the word is RELATED to so the dictionary agrees. Yet, what the dictionary doesn't explain in details (and dictionaries don't say the whole truth) is WHY THE SLAVS PREFERED THE SELF-DESIGNATION . That counts indeed.
Also, although the dictionary expresses an idea already believed (and in the path of science linguistic has to be understood according to recent historical facts and hence, always changing and not saying the ultimate truth), the dictionary doesn't deny. It says an opinion: "is BETTER than slave". My source is not a mere linguist expert in one or two languages but a guy who was fluent in 30 languages and that was named in People's Almanac in the list of the bigger 15 linguists in the world. Not just a dictionary....with all do respect.