In some situations, a common noun in a specific scenario is treated as a proper noun because it refers to a specific entity that satisfies the common noun.
Is there a special term for this phenomenon?
Examples:
"Go ask his father", said the teacher. vs "Go ask Father", said the mother.
and
"Most city halls have them", she replied. vs "City Hall has them", he stated.
Best Answer
In conventional resources on common and proper nouns, they are treated as two separate subcategories of noun.
Some sources do consider converting one kind of noun to another. Here is ThoughtCo author Richard Nordquist on going from a common to proper noun. The only applicable verb in the article is capitalize, referring to the change in form that signals a proper noun:
However, in more academic contexts linguists have referred to the creation of proper nouns (single words) or proper names (noun phrases) as naming. Adrienne Lehrer in "Names and Naming: Why We Need Fields and Frames" describes the conventions of naming:
Another author, Willy Van Langendonck, describes this process as naming when summarizing a theory of proper name formation in Theory and Typology of Proper Names:
So naming forms a proper name or noun from (usually) a common noun or (occasionally) other parts of speech.
The reverse process is appellatization, described in The Dictionary of Historical and Comparative Linguistics as
and cites aspirin and Kleenex as examples. Its verb form (appellativize) is turgid and technical.