na-adjective, noun which may take the genitive case particle 'no', noun
infinitesimal; very small; minute
Describes an extremely small amount, difference, or change, often in scientific or formal contexts. Can be used as a noun, na-adjective, or no-adjective.
In this experiment, even an infinitesimal error is not allowed.
The outcome was decided by a very small margin.
Compound of 微 (bi, 'minute') and 少 (shō, 'small'). The spelling 微少 is a variant of the more common 微小, with 少 emphasizing smallness in quantity or degree rather than physical size.