1. extremely small; so small as to be almost nothing

1. an infinitely small quantity
Usage: mathematics

Examples

• The chance of winning the lottery is infinitesimal.
• She made infinitesimal adjustments to the microscope.
• The difference between the two measurements was infinitesimal.
• Even an infinitesimal amount of the poison could be deadly.
• The artist painted with infinitesimal brushstrokes.
• In calculus, we work with infinitesimals to find derivatives.
• The infinitesimal particles were barely detectable.