■ noun
1》 an individual thing or person regarded as single and complete but also able to form a individual component of a larger whole.
↘a self-contained section of a building or group of buildings.
↘a subdivision of a larger military grouping.
↘a self-contained part of an educational course.
↘a single manufactured item.
2》 a device or part with a specified function.
3》 a standard quantity in terms of which other quantities may be expressed.
4》 one as a number or quantity.
Derivatives
~ize or ~ise verb
Origin
C16: from L. unus , prob. suggested by digit .