spurious

Lacking authenticity or validity in essence or origin; not genuine.

Not trustworthy; dubious or fallacious.

Born to unwed parents.

Not legitimate; bastard: as, spurious issue.

Not proceeding from the true source or from the source pretended; not being what it pretends or appears to be; not genuine; counterfeit; false; adulterated.

In zoology:

False; resembling a part or organ, but not having its function: as, spurious eyes or limbs.

Having the functions of an organ, but morphologically different from it: as, the spurious legs, or prolegs, of a caterpillar.

Aborted or changed so that the normal functions no longer exist: as, the spurious or aborted front legs of certain butterflies.

Erroneous; incorrectly established: as, a spurious genus or species. See pseudogenus.