Joking aside: AFAIK is @OlegHahm's explanation the right one: 6LoWPAN used to mean IPv**6** over **Lo**w Power **W**ireless **P**ersonal **A**rea **N**etworks (and is noted like this in Wikipedia e.g., still), but it shifted to IPv**6** over **Lo**w **P**ower Wireless **A**rea **N**etworks a while ago (since the Personal constraint is not fitting anymore).