1. A unit of time equal to one quadrillionth of a second (10⁻¹⁵ seconds).
Usage: technical; scientific

Examples

• Femtosecond lasers can measure events that occur in incredibly short time intervals.
• The chemical reaction was studied using femtosecond spectroscopy to observe molecular dynamics.
• A femtosecond is to a second what a second is to about 31.7 million years.
• Researchers used femtosecond pulses to capture images of electrons moving within atoms.
• The experiment required precision timing measured in femtoseconds.