something called ...; something like ...
Used to refer to a thing or concept by name, often with a nuance of 'the thing known as ...' or 'what you call ...'. Can be used to define or characterize something.
Love is something you cannot see.
He values what is called friendship.
というもの refers to a thing or concept by name within a sentence, while というのは introduces a definition or explanation of a term, often translated as 'the reason is' or 'that is to say'.
Kanji spelling using 言う; less common but still encountered.
Kanji spelling using 物; rare and may be seen in older or formal writing.
Full kanji spelling; very rare and mostly found in older texts.
Combination of quotative particle と, verb 言う (to say), and generic noun 物 (thing). Literally 'the thing one calls ...'.