[Haskell-cafe] What to call Occult Effects

By an occult effect I mean that under the type signature (M a -> M b -> M b) of a particular monad M, the two expressions (const id) and (liftM2 $ const id) are equivalent. Occult here refers to how the effect of the second parameter blocks the effect of the first one. In your opinion, is there a better word than occult to describe the property of such monads? -- -- Kim-Ee