1. A unit of length equal to one trillionth of a metre (10⁻¹² m), used in physics and chemistry to measure atomic and subatomic distances.
Usage: Also spelled picometer in U.S. English.; Commonly used in scientific and technical contexts.

Examples

• The diameter of a hydrogen atom is approximately 100 picometres.
• Researchers measured the bond length in picometres using X-ray crystallography.
• A picometre is one millionth of a nanometre.
• The wavelength of gamma rays can be expressed in picometres.
• Atomic radii are typically given in picometres in chemistry textbooks.