Erroneous, a.
Etymology: [L. erroneus, fr. errare to err. See Err.]
1. Wandering; straying; deviating from the right course; -- hence, irregular; unnatural. [Obs.] "Erroneous circulation." Arbuthnot. Stopped much of the erroneous light, which otherwise would have disturbed the vision. Sir I. Newman.
2. Misleading; misled; mistaking. [Obs.] An erroneous conscience commands us to do what we ought to omit. Jer. Taylor.
3. Containing error; not conformed to truth or justice; incorrect; false; mistaken; as, an erroneous doctrine; erroneous opinion, observation, deduction, view, etc. -- Er*ro"ne*ous*ly, adv. -- Er*ro"ne*ous*ness, n.
Shades of meaning
Fernald has no entry of its own for erroneous; he lists it under absurd.
Where he writes about it:
Anything is irrational when clearly contrary to sound reason, foolish when contrary to practical good sense, silly when petty and contemptible in its folly, erroneous when containing error that vitiates the result, unreasonable when there seems a perverse bias or an intent to go wrong. — from absurd