U

that is

pronoun, plural those.

(used to indicate a person, thing, idea, state, event, time, remark, etc., as pointed out or present, mentioned before, supposed to be understood, or by way of emphasis): That is her mother. After that we saw each other.
(used to indicate one of two or more persons, things, etc., already mentioned, referring to the one more remote in place, time, or thought; opposed to this): This is my sister and that’s my cousin.
(used to indicate one of two or more persons, things, etc., already mentioned, implying a contrast or contradistinction; opposed to this): This suit fits better than that.
(used as the subject or object of a relative clause, especially one defining or restricting the antecedent, sometimes replaceable by who, whom, or which): the horse that he bought.
(used as the object of a preposition, with the preposition standing at the end of a relative clause): the farm that I spoke of.
(used in various special or elliptical constructions): fool that he is.

adjective, plural those.

(used to indicate a person, place, thing, or degree as indicated, mentioned before, present, or as well-known or characteristic): That woman is her mother. Those little mannerisms of hers make me sick.
(used to indicate the more remote in time, place, or thought of two persons, things, etc., already mentioned; opposed to this): This room is his and that one is mine.
(used to imply mere contradistinction; opposed to this): not this house, but that one.

adverb

(used with adjectives and adverbs of quantity or extent) to the extent or degree indicated: that much; The fish was that big.
to a great extent or degree; very: It’s not that important.
Dialect. (used to modify an adjective or another adverb) to such an extent: He was that weak he could hardly stand.

conjunction

(used to introduce a subordinate clause as the subject or object of the principal verb or as the necessary complement to a statement made, or a clause expressing cause or reason, purpose or aim, result or consequence, etc.): I’m sure that you’ll like it. That he will come is certain. Hold it up so that everyone can see it.
(used elliptically to introduce an exclamation expressing desire, a wish, surprise, indignation, or other strong feeling): Oh, that I had never been born!

Idioms

at that,
1. in spite of something; nevertheless: Although perhaps too elaborate, it seemed like a good plan at that.
2. in addition; besides: It was a long wait, and an exasperating one at that.
that is, (by way of explanation, clarification, or an example); more accurately: I read the book, that is, I read most of it. I believe his account of the story, that is to say, I have no reason to doubt it.Also that is to say.
that’s that, Informal. there is no more to be said or done; that is finished: I’m not going, and that’s that!
that way, Informal. in love or very fond of (usually followed by about or for): The star and the director are that way. I’m that way about coffee.
with that, following that; thereupon: With that, he turned on his heel and fled.

determiner (used before a singular noun)

1. used preceding a noun that has been mentioned at some time or is understoodthat idea of yours
2. (as pronoun)don’t eat that; that’s what I mean
1. used preceding a noun that denotes something more remote or removedthat dress is cheaper than this one; that building over there is for sale
2. (as pronoun)that is John and this is his wife; give me that Compare this
used to refer to something that is familiarthat old chap from across the street
and that or and all that informal everything connected with the subject mentionedhe knows a lot about building and that
at that (completive-intensive) additionally, all things considered, or neverthelesshe’s a pleasant fellow at that; I might decide to go at that
like that
1. with ease; effortlesslyhe gave me the answer just like that
2. of such a nature, character, etche paid for all our tickets — he’s like that
that is
1. to be precise
2. in other words
3. for example
that’s more like it that is better, an improvement, etc
that’s that there is no more to be done, discussed, etc
with that or at that thereupon; having said or done that

conjunction (subordinating)

used to introduce a noun clauseI believe that you’ll come
Also: so that, in order that used to introduce a clause of purposethey fought that others might have peace
used to introduce a clause of resulthe laughed so hard that he cried
used to introduce a clause after an understood sentence expressing desire, indignation, or amazementoh, that I had never lived!

adverb

used with adjectives or adverbs to reinforce the specification of a precise degree already mentionedgo just that fast and you should be safe
Also: all that (usually used with a negative) informal (intensifier)he wasn’t that upset at the news
dialect (intensifier)the cat was that weak after the fight

pronoun

used to introduce a restrictive relative clausethe book that we want
used to introduce a clause with the verb to be to emphasize the extent to which the preceding noun is applicablegenius that she is, she outwitted the computer

pron.Old English þæt, neuter singular of the demonstrative pronoun and adjective (corresponding to masc. se, fem. seo), from Proto-Germanic *that, from PIE *tod-, extended form of demonstrative pronomial base *to- (cf. Sanskrit ta-, Lithuanian and Old Church Slavonic to, Greek to “the,” Latin talis “such”). Cf. the. Emerged c.1200 as a demonstrative adjective with the breakdown of the Old English grammatical gender system, perhaps by influence of French and Latin, which had demonstrative adjectives (Old English did not). Slang that way “in love” first recorded 1929. That-a-way is recorded from 1839. “Take that!” said while delivering a blow, is recorded from early 15c. Also, that is to say. To explain more clearly, in other words, as in It’s on the first floor, that is, at street level, or We’re coming next month, that is to say, in November. [Early 1600s] Also see under that’s. In addition to the idioms beginning with that

that ain’t hay

that does it

that is

that makes two of us

that will do

also see:

all’s well that ends well

all that

all that glitters is not gold

and all (that)

as far as that goes

at that point

at this (that) rate

at this (that) stage

be that as it may

bite the hand that feeds you

cross a (that) bridge

for that matter

game that two can play

how about that

how does that grab you

how’s that

in order (that)

in that

is that a fact

it (that) figures

just like that

just the (that’s the) ticket

last straw (that breaks)

like that

look like the cat that ate the canary

not all that

not built that way

now that

on condition that

on the chance (that)

powers that be

put that in your pipe

seeing that

ships that pass in the night

so that

suffice it to say that

tear (that tears) it

this and that

to that effect

when it comes to (that)

would that

you can say that again