The general name which applies to a thing by virtue of its being the first correlate of a relation is called a relative.
Our European languages are peculiar in their marked differentiation of common nouns from verbs. Proper nouns must exist in all languages; and so must such “pronouns,” or indicative words, as this, that, something, anything. But it is probably true that in the great majority of the tongues of men, distinctive common nouns either do not exist or are exceptional formations. In their meaning as they stand in sentences, and in many comparatively widely-studied languages, common nouns are akin to participles, as being mere inflexions of verbs. If a language has a verb meaning “is a man,” a noun “man” becomes a superfluity. For all men are mortals is perfectly expressed by “Anything either is-a-man not or is-a-mortal.” Some man is a miser is expressed by “Something both is-a-man and is-a-miser.” The best treatment of the logic of relatives, as I contend, will dispense altogether with class names and only use such verbs. A verb requiring an object or objects to complete the sense may be called a complete relative.
A verb by itself signifies a mere dream, an imagination unattached to any particular occasion. It calls up in the mind an icon. A relative is just that, an icon, or image, without attachments to experience, without “a local habitation and a name,” but with indications of the need of such attachments.
A relative […] may be defined as the equivalent of a word or phrase which, either as it is (when I term it a complete relative), or else when the verb “is” is attached to it (and if it wants such attachment, I term it a nominal relative), becomes a sentence with some number of proper names left blank.
If from any proposition having more than one subject (used to include “objects”) we strike out the indices of the subjects, as in “– praises – to –,” “– dat in matrimonium –,” what remains and requires at least two insertions of subject-nouns to make a proposition is a “relative term,” or “relative rhema,” called briefly a “relative.” The relative may be converted into a complete assertion by filling up the blanks with proper names or abstract nouns; this serves as a criterion.
A rhema of more than one blank is a relative.
A predicate of more than one blank is called a relative predicate.
…a relative, or relative term, is a word, phrase, or sign fit to be the predicate of an assertion but requiring the affixion of more than one subject in order to complete the fully explicit expression of the matter of an assertion, a dyadic relative requiring two subjects, etc.
From an alternate fragment [MB]