Talk:Abstract object theory
|WikiProject Philosophy||(Rated Stub-class)|
|WikiProject Physics||(Rated Start-class, Low-importance)|
the meaning of abstract as opposed to concrete, the property of definite (defined) visible and tangible objects around us is not confined to that sense. There is a continuum between defined and undefined state of objects subject to the observer's stance. Just as matter has different physical states for instance plasma, gaseous, fluent and rigid where the definition of borders is increasingly difficult and requires shift in scale or distance of observation, the way you can think of something as abstract depends on whether you have that abstract noun generated by different mental operations.
Also, a non abstract noun, such as a table may also be seen as undefined, hence abstract (in the abstract), if the word has an indefinite article, or a plural form, or a definite article meaning the class of that object.
Now abstract nouns in the above interpretation are an easy job. But it should be noted that all relations, and properties (attributes) are abstract by definition, since they have no tangible (spatio-temporal) referents. Mind you, relations are represented by verbs, and if someone suggests otherwise, it is easy to point out that any other point is wrong.