submicron
/sʌbˈmʌɪkrɒn/noun
1A particle less than a micron in size.
2A measure of length equal to one tenth of a micron (1 × 10−7 metre).
adjective
Less than a micron in size or length; relating to or involving such a size.
Origin
Early 20th century; earliest use found in Science. From sub- + micron.