äït

þæt is the neuter singular form of the Old English demonstrative pronoun and determiner, and it also functions as a relative pronoun and as a conjunction. In Old English, it commonly means “that” and is used to point to or identify a following noun, to mark definiteness before neuter nouns, and to introduce dependent or relative clauses.

Etymology and cognates: þæt derives from a proto-Germanic demonstrative base, with cognates across Germanic languages such as Old Norse thát (það), Icelandic það, German das, Dutch dat, and Gothic þat. The form reflects a shared neuter demonstrative core in the West Germanic family.

Morphology and syntax: As a determiner before neuter nouns, þæt marks a definite reference equivalent to “that” in English. As a pronoun, it can stand for a neuter antecedent. In Old English, it declined for case, with neuter singular forms including þæt in the nominative/accusative, and with genitive and dative forms such as þæs and þæm in certain dialects. As a relative pronoun, þæt can introduce clauses referring to a neuter antecedent; as a conjunction, it introduces embedded clauses parallel to the Modern English complementizer “that.”

History and usage: The form features prominently in Old English texts from the 9th to the 11th centuries. The written representation used the thorn letter þ to convey the th-sound; as English orthography evolved, the thorn was largely replaced by the digraph th, and þ fell out of standard English, though it survives in Icelandic and in scholarly editions of Old English.

Legacy: In linguistic descriptions of Old English, þæt is analyzed as the neuter demonstrative pronoun and complementizer, and it is linked to the development of the modern English pronoun and conjunction “that.”