I enjoyed this Supreme Court exchange around the term “orthogonal” and, even more, the discussion that followed in the comments. I use the terms “tangential” and “orthogonal” (correctly, and not interchangeably), though less often than I used to because it takes more time to explain than to simply use different terminology… or just avoid the whole idea altogether. Conceptually, though, particularly in the context of information fluency and contemporary teaching and learning that uses the network metaphor, I think understanding the two terms– and orthogonal in it’s fullest sense– is nearly a necessity.