Old English þæt, "that, so that, after that," neuter singular demonstrative pronoun ("A Man's a Man for a' that"), relative pronoun ("O thou that hearest prayer"), and demonstrative adjective ("Look at that caveman go!"), corresponding to masc. se, fem. seo. From Proto-Germanic *that, from PIE *tod-, extended form of demonstrative pronominal base *-to- (see -th (1)).

With the breakdown of the grammatical gender system, it came to be used in Middle English and Modern English for all genders. Germanic cognates include Old Saxon that, Old Frisian thet, Middle Dutch, Dutch dat "that," German der, die, das "the."

Generally more specific or emphatic than the, but in some cases they are interchangeable. From c. 1200 opposed to this as indicating something farther off. In adverbial use ("I'm that old"), in reference to something implied or previously said, c. 1200, an abbreviation of the notion of "to that extent," "to that degree." As a conjunction ("Not that I loved Caesar less, but that I loved Rome more") it was originally the neuter pronoun or adjective that used practically as a definite article qualifying the whole sentence.

Slang that way "in love" first recorded 1929. That-a-way "in that direction" is recorded from 1839. "Take that!" said while delivering a blow, is recorded from early 15c.

1837, from Greek hoi polloi (plural) "the people," literally "the many" (plural of polys, from PIE root *pele- (1) "to fill"). Used in Greek by Dryden (1668) and Byron (1822), in both cases preceded by the, even though Greek hoi means "the," a mistake repeated often by subsequent writers who at least have the excuse of ignorance of Greek. Ho "the" is from PIE *so- "this, that" (nominative), cognate with English the and Latin sic. From the adjective agoraios "pertaining to the agora; frequenting the market" Greek had hoi agoraioi "loungers in the market, loafers, common, low men."

c. 1200, "that not," especially "for fear that" [OED calls it a negative particle of intention], from a contraction of the Old English phrase þy læs þe "the less that," from þy, instrumental case of demonstrative article þæt "that" + læs (see less) + conjunction þe (see the). The þy was dropped and the remaining two words contracted into early Middle English leste.

in phrase for the nonce (Middle English for þe naness, c. 1200) "for a special occasion, for a particular purpose," a misdivision (see N for other examples) of for þan anes "for the once," in reference to a particular occasion or purpose, the þan being an altered form of the Middle English dative definite article þam (see the). The phrase was used from early 14c. as an empty filler in metrical composition.

"the female person referred to," third person nominative fem. pronoun, used as a substitute for the name of a female or anything regarded as female, mid-12c., probably evolving from Old English seo, sio (accusative sie), fem. of the demonstrative pronoun (masc. se) "the," from PIE root *so- "this, that" (see the).

The Old English word for "she" was heo, hio, however by 13c. the pronunciation of this had converged by phonetic evolution with he "he," which apparently led to the fem. demonstrative pronoun being used in place of the pronoun (compare similar development in Dutch zij, German sie, Greek he, etc.).

The original h- survives in her. A relic of the Old English pronoun is in Manchester-area dialectal oo "she." As a noun meaning "a female human being, a woman," she is attested from early 14c. Also used to signify "female" with the names of other creatures (late 14c.; she-wolf, etc.). The attempted gender-neutral pronoun form s/he is attested by 1977.

adverb of time, Old English þanne, þænne, þonne, from Proto-Germanic *thana- (source also of Old Frisian thenne, Old Saxon thanna, Dutch dan, Old High German danne, German dann), from PIE demonstrative pronoun root *to- (see the).

As a conjunction, "in that case, therefore," in Old English. As an adjective, "being at that time," from 1580s. As a noun from early 14c. For further sense development, see than. Similar evolutions in other Germanic languages; Dutch uses dan in both senses, but German has dann (adv.) "then," denn (conj.) "than." Now and then "at various times" is attested from 1550s; earlier then and then (c. 1200).

late 13c., from Old English þanone, þanon "from that place" + adverbial genitive -es. Old English þanone/þanon is from Proto-Germanic *thanana (source also of Old Saxon thanana, Old Norse þana, Old Frisian thana, Old High German danana, German von dannen), related obscurely to the root of then, and ultimately from PIE demonstrative base *to- (see the). Written with -c- to indicate a voiceless "s" sound. Meaning "from that time" is from late 14c.; sense of "for that reason" is from 1650s. From thence is redundant.

Old English þær "in or at that place, so far as, provided that, in that respect," from Proto-Germanic *thær (source also of Old Saxon thar, Old Frisian ther, Middle Low German dar, Middle Dutch daer, Dutch daar, Old High German dar, German da, Gothic þar, Old Norse þar), from PIE *tar- "there" (source also of Sanskrit tar-hi "then"), from root *to- (see the) + adverbial suffix -r.

Interjectional use is recorded from 1530s, used variously to emphasize certainty, encouragement, or consolation. To have been there "had previous experience of some activity" is recorded from 1877.

"that same, the very thing," early 13c., contraction from þe "the" (see the) + ilce "same" (see ilk).

old or quaintly archaic way of writing the, in which the -y- is a 16c. graphic alteration of þ, an Old English character (generally called "thorn," originally a Germanic rune; see th) that represented the -th- sound (as at the beginning of thorn). The characters for -y- and -þ- so closely resembled each other in Old English and early Middle English handwriting that a dot had to be added to the -y- to keep them distinct. In late 15c., early printers in English, whose types were founded on the continent, did not have a þ in their sets, so they substituted y as the letter that looked most like it when setting type. But in such usages it was not meant to be pronounced with any of the sounds associated with -y-, but still as "-th-." Ye for the (and yt for that) continued in manuscripts through 18c. Revived 19c. as a deliberate antiquarianism; the Ye Olde _____ construction was being mocked by 1896.