Terminology

Concrete terms refer to objects or events that are available to the senses. [This is directly opposite to abstract terms, which name things that are not available to the senses.] Examples of concrete terms include spoon, table, velvet eye patch, nose ring, sinus mask, green, hot, walking.

Because these terms refer to objects or events we can see or hear or feel or taste or smell, their meanings are pretty stable. If you ask me what I mean by the word spoon, I can pick up a spoon and show it to you. [I can't pick up a freedom and show it to you, or point to a small democracy crawling along a window sill. I can measure sand and oxygen by weight and volume, but I can't collect a pound of responsibility or a liter of moral outrage.] 

While abstract terms like love change meaning with time and circumstances, concrete terms like spoon stay pretty much the same. Spoon and hot and puppy mean pretty much the same to you now as they did when you were four. 

POLYGNOSIS is an abstract term though it is a content word.

Content words are words that have meaning. They can be compared to grammatical words, which are structural. Nouns, main verbs, adjectives and adverbs are usually content words. Auxiliary verbs, pronouns, articles, and prepositions are usually grammatical words.

Example
‘We flew over the mountains at dawn'.