That
That is a function word used in the English language for several grammatical purposes.These include:
as a complementizer/subordinating conjunction. (“He asked that she go.”)
to introduce a restrictive relative clause (“The test that she took was hard.”) In this role, that may be analyzed either as a relative pronoun or as a conjunction as in the first case; see English relative clauses: That as relativizer instead of relative pronoun. (In American and Canadian English, “that” is only used in this way if the verb could affect the proceeding noun, i.e., one would say “The test she took was hard,” but would still say “I hate that dogs are messy” to avoid being misheard as saying “I hate dogs.”)
as a demonstrative pronoun (“That was hard.”) (plural: those)
as a demonstrative adjective (“That test was hard.”) (plural: those)
as an adverb (“The test wasn’t that bad.”)In the first two uses the word is usually pronounced weakly, as /ðət/, whereas in the other uses it is pronounced /ðæt/.
In the Old English language that was spelled þæt. It was also abbreviated as a letter Thorn, þ, with the ascender crossed, ꝥ ( ). In Middle English, the letter Ash, æ, was replaced with the letter a, so that that was spelled þat, or sometimes þet. The ascender of the þ was reduced (making it similar to the Old English letter Wynn, ƿ), which necessitated writing a small t above the letter to abbreviate the word that ( ). In later Middle English and Early Modern English the þ evolved into a y shape, so that the word was spelled yat (although the spelling with a th replacing the þ was starting to become more popular) and the abbreviation for that was a y with a small t above it ( ). This abbreviation can still be seen in reprints of the 1611 edition of the King James Version of the Bible in places such as 2 Corinthians 13:7.
That is often omitted when used to introduce a subordinate clause—”He told me that it is a good read.” could just as easily be “He told me it is a good read.” Historically, “that” usually followed a comma: “He told me, that it is a good read.” Middle Modern English grammarian Joseph Robertson recommended in On Punctuation that a comma be used with a conjunction. However, if the subordinate, conjunctional ellipse, null complement, or syntactic pleonasm of “that” is punctuated with a comma, then, in the English grammar, stylistically speaking, it is a comma splice, especially in formal writing. Instead, a semicolon should be used to be grammatically correct:
He told me; it is a good read. In grammar, the usage of “that” constitutes a that-clause while its absence constitutes a bare clause.
This (determiner)
The (thing) here used in indicating something or someone nearby.
“This classroom is where I learned to read and write.”
This (determiner)
The known (thing) used in indicating something or someone just mentioned.
“They give the appearance of knowing what they’re doing. It’s this appearance that lets them get away with so much.”
This (determiner)
The known (thing) used in indicating something or someone about to be mentioned.
“When asked what he wanted for his birthday, he gave this reply: “[…]””
This (determiner)
A known (thing) used in first mentioning a person or thing that the speaker does not think is known to the audience. Compare with “a certain …”.
“I met this woman the other day who’s allergic to wheat. I didn’t even know that was possible!”
“There’s just this nervous mannerism that Bob has with his hands, and it drives me crazy.”
This (determiner)
which is current.
“It snowed this week.”
This (adverb)
To the degree or extent indicated.
“I need this much water.”
“Do we need this many recommendations?”
“We’ve already come this far, we can’t turn back now.”
This (pronoun)
The thing, item, etc. being indicated.
“This is the excellent foppery of the world, that, when we are sick in fortune,—often the surfeit of our own behaviour,—we make guilty of our disasters the sun, the moon, and the stars… — Shakespeare, King Lear, [http://en.wikisource.org/w/index.php?title=The_Tragedy_of_King_Lear&action=edit§ion=4 Act 1. Scene 2.]”
This (noun)
Something being indicated that is here; one of these.
This (interjection)
Indicates the speaker’s strong approval or agreement with the previous material.
That (conjunction)
Introducing a clause which is the subject or object of a verb (such as one involving reported speech), or which is a complement to a previous statement.
“He told me that the book is a good read.”
“I believe that it is true. — She is convinced that he is British.”
That (conjunction)
Introducing a subordinate clause expressing a reason or cause: because, in that.
“Be glad that you have enough to eat.”
That (conjunction)
Introducing a subordinate clause that expresses an aim, purpose{{, or goal (“final”), and usually contains the auxiliaries may, might{{,}} or should:}} so, so that.
That (conjunction)
Introducing — especially, but not exclusively, with an antecedent like so or such — a subordinate clause expressing a result, consequence{{, or effect.}}
“The noise was so loud that she woke up.”
“The problem was sufficiently important that it had to be addressed.”
That (conjunction)
Introducing a premise or supposition for consideration: seeing as; inasmuch as; given that; as would appear from the fact that.
That (conjunction)
Introducing a subordinate clause modifying an adverb.
“Was John there? — Not that I saw.”
“How often did she visit him? — Twice that I saw.”
That (conjunction)
Introducing an exclamation expressing a desire or wish.
That (conjunction)
Introducing an exclamation expressing a strong emotion such as sadness or surprise.
That (determiner)
The (thing, person, idea, etc) indicated or understood from context, especially if more remote physically, temporally or mentally than one designated as “this”, or if expressing distinction.
“That book is a good read. This one isn’t.”
“That battle was in 1450.”
“That cat of yours is evil.”
That (pronoun)
The thing, person, idea, quality, event, action{{,}} or time indicated or understood from context, especially if more remote geographically, temporally or mentally than one designated as “this”, or if expressing distinction. from 9thc.
“He went home, and after that I never saw him again.”
That (pronoun)
The known (thing); used to refer to something just said.
“They’re getting divorced. What do you think about that?”
That (pronoun)
The aforementioned quality; used together with a verb and pronoun to emphatically repeat a previous statement.
“The water is so cold! — That it is.”
That (pronoun)
(plural that) Which, who; representing a subject, direct object, indirect object, or object of a preposition. from 9thc.
“The CPR course that she took really came in handy.”
“The house that he lived in was old and dilapidated.”
That (adverb)
To a given extent or degree.
“”The ribbon was that thin.” “I disagree, I say it was not that thin, it was thicker… or maybe thinner…””
That (adverb)
To a great extent or degree; very, particularly in negative constructions.
“I’m just not that sick.”
“I did the run last year, and it wasn’t that difficult.”
“so”
That (adverb)
To such an extent; so. in positive constructions.
“Ooh, I was that happy I nearly kissed her.”
That (noun)
Something being indicated that is there; one of those.