spurious

According to G.R. Watson's The Roman Soldier, the word "spurious" arises from the family name Spurius. In the Roman army—specifically, the auxiliaries—when an illegitimate son came into the service, he was annotated with sp, standing for sine patre, or, "without father," because officially, the records had to contain a family name. Since Sp is also the abbreviation for Spurius—such things were often abbreviated and the Latin alphabet in Roman times had no distinction between lower and upper case—it's easy to see how the term arose.

Spu"ri*ous (?), a. [L. spurius.]

1.

Not proceeding from the true source, or from the source pretended; not genuine; false; adulterate.

2.

Not legitimate; bastard; as, spurious issue.

Milton.

Spurious primary, ∨ Spurious quill Zool., the first, or outer, primary quill when rudimentary or much reduced in size, as in certain singing birds. -- Spurious wing Zool., the bastard wing, or alula.

Syn. -- Counterfeit; false; adulterate; supposititious; fictitious; bastard.

-- Spu"ri*ous*ly, adv. -- Spu"ri*ous*ness, n.

© Webster 1913.