Backronyms ahoy! Bipedal Offense Transport System Basic Overland Tactical Soldier Ballistic Offense Troop Solution I'm struggling for TANK though; Tracked Armoured something something is as far as I get
I think it should be pronounced oobot, that would make it sound like "U-Boot", which itself means "submarine" in german, thus making it kind of a pun. (Ultra-mobile Bipedal Offense Transport System?)