"Case" is a linguistics term regarding a manner of categorizing nouns, pronouns, adjectives, participles, and numerals according to their traditionally corresponding grammatical functions within a given phrase, clause, or sentence. In some languages, nouns, pronouns, adjectives, determiners, participles, prepositions, numerals, articles and their modifiers take different inflected forms, depending on their case.
Among others, according to Steven Pinker's The Sense of Style: The Thinking Person's Guide to Writing in the 21st Century:
The marking of a noun to indicate its grammatical function, including nominative case (for subjects), genitive case (for determiners, including possessives), and accusative case (for objects and everything else).
To my reading, according to Wikipedia definition, the marking of the noun (inflection) is not an inseparable element of the term
case; but according to the other definition,
case, in a sense, is the “marking of a noun to indicate its grammatical function.” (Even though languages such as English has largely lost its inflected case system.)
Put another way, would the linguistic term
case exist had there been no such thing as inflection?
The following quote from the book Theories of Case by Miriam Butt (suggested by @purlupar) makes me even more confused:
English does not allow the same freedom in word order as Latin. Instead of overt marking on the noun, it makes use of the position of of the noun in the sentence in order to indicate the seer vs. the thing being seen. (p.4)
Again, to my reading, the quote suggests that
marking is not supposed to be in the form of overt morphological markers, but using position (or word order) is also a way of