Biohazard

engineered to mean nothing

Unicode: U+2623 biohazard sign
Meaning: Biological hazard. The mark carries no pictorial content whatsoever — no cell, no skull, no organism.
History: Designed in 1966 by Charles Baldwin, an environmental-health engineer at Dow Chemical, with Dow’s packaging designers, and published in Science the following year. The brief was unusual: the symbol had to be memorable and meaningless. Candidates were tested nationally for how well people recalled them and for how few existing associations they carried, so the winner would be unmistakable precisely because it resembled nothing already in use. It was also required to be symmetrical enough to read from any angle and simple enough to stencil.
Variants: Fixed by standard; the colour ground varies by jurisdiction.
Related: ☢ ⚠ Radiation, and the ISO 7010 warning set.
Appears: Laboratory and clinical waste, transport labelling, quarantine signage.
Evolution: Blank by design → regulated warning → pop-culture shorthand for contagion, which quietly undoes the meaninglessness it was built on.

Sources · 3

documented C. L. Baldwin and R. S. Runkle, “Biohazards Symbol: Development of a Biological Hazards Warning Signal”, Science, 1967 — the design criteria and the testing method, stated by the designers themselves.
documented ISO 7010 W009, the current biological-hazard warning sign.
documented The Unicode Standard, U+2623 BIOHAZARD SIGN.