Pseudis paradoxa, a species of frog unusual because it is larger as a tadpole (up to 25 cm or 10 in. long) than as an adult (about a quarter of that length).

A paradox that occurs in naive set theory or naive logics, and allows the derivation of an arbitrary sentence from a self-referring sentence and some apparently innocuous logical deduction rules.

Synonym of Curry's paradox

(economics) A paradox of economics, stating that an increase in autonomous saving leads to a decrease in aggregate demand and thus a decrease in gross output which will in turn lower total saving: narrowly speaking, total saving may fall because of individuals' attempts to increase their saving, and, broadly speaking, increase in saving may be harmful to an economy.

The linguistic paradox that, if there are unnameable things, their existence cannot be indicated without naming them in some way.

The observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism.

A logical paradox resembling the liar paradox but using, instead of a single sentence, an infinite sequence of statements, each referring to the truth values of the later statements in the sequence, and thus attempting to avoid circularity.

(quantum mechanics) A surprising result of applying the Dirac equation to the problem of electron scattering from a potential barrier. In non-relativistic quantum mechanics, electron tunnelling into a barrier is observed, with exponential damping. However, if the potential is of the order of the electron mass, V∼mc², the barrier is nearly transparent; moreover, as the potential approaches infinity, the reflection diminishes and the electron is always transmitted.

(economics) The apparent paradox that a rent seeker wanting political favours can bribe politicians at a cost much lower than the value of the favour to the rent seeker.

(physics) The black hole information paradox.