Paradox, n.; pl. Paradoxes.
Etymology: [F. paradoxe, L. paradoxum, fr. Gr. Para-, and Dogma.]
A tenet or proposition contrary to received opinion; an assertion or sentiment seemingly contradictory, or opposed to common sense; that which in appearance or terms is absurd, but yet may be true in fact. A gloss there is to color that paradox, and make it appear in show not to be altogether unreasonable. Hooker. This was sometime a paradox, but now the time gives it proof. Shak. Hydrostatic paradox. See under Hydrostatic.
Shades of meaning
Fernald has no entry of its own for paradox; he lists it under riddle.
Where he writes about it:
Conundrum, a word of unknown origin, signifies some question or statement in which some hidden and fanciful resemblance is involved, the answer often depending upon a pun; an enigma is a dark saying; a paradox is a true statement that at first appears absurd or contradictory; a problem is something thrown out for solution; puzzle (from oppose) referred originally to the intricate arguments by which disputants opposed each other in the old philosophic schools. — from riddle