You may think that “Webelos” has always stood for “WE’ll BE LOyal Scouts.”
But actually, “Webelos” originally stood for the first letters of the ranks leading up to Boy Scouting: Wolf, Bear, Lion, Scout.
The term is explained in this excerpt from the 1948 Lion Cub Scout Book:
“The name WEBELOS (say Wee-belos) is like the name of an Indian tribe. It’s the word to use when you want to talk about all of the boys everywhere who are Cub Scouts.
The letters W-B-L-S in Webelos are the first letters of the Cub Scout Ranks which lead up to Boy Scouting — WOLF, BEAR, LION, SCOUT.
The highest rank in Cub Scouting, after Lion, is the Webelos Rank. A Webelos Cub Scout is one who is fully prepared to become a Boy Scout and join a troop when he is twelve years old.
The Arrow of Light, shown above, is used for the Webelos Badge. The Arrow of Light stands for advancement along the trail from Wolf, all the way up to Boy Scout.” [Bold added]