Abstract labor (n.) is labor viewed through the lens of capitalism, which has the astounding ability to extract out or 'abstract' one common unit of measure and apply it universally to the labor of so many different histories and peoples.
Abstract labor (n.) is work done simply in order to earn a wage rather than for the worker's own specific purposes.
Abstract labor (n.) is labor with the individuality of the worker boiled out of it.
Abstract labor (n.) under commodity production is the form in which social labour becomes social only by taking the form of its direct opposite.
Abstract labor (n.) is an old abstraction that became true in practice only in modern America, where people pass easily from one job to another and do not care which falls to their share.