that

conjunction

1. Introducing a clause that is the object of a verb, especially a reporting verb or verb expressing belief, knowledge, perception, etc.

   “He told me that the book is a good read.”

2. Introducing a clause that is the subject of a verb, especially the 'be' verb or a verb expressing judgement, opinion, etc. As delayed subject.

   “It is almost certain that she will come.”

3. As delayed subject.

   “It is almost certain that she will come.”

4. As direct subject.

   “That she will come is almost certain.”

determiner

1. 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.”

pronoun

1. 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. .mw-parser-output .defdate{font-size:smaller}

   “That's my car over there.”

2. Used to refer to a noun phrase or statement just made.

   “They're getting divorced. What do you think about that?”

3. Used to emphatically affirm or deny a previous statement or question.

   “The water is so cold! — That it is.”

4. In a relative clause, referring to a previously mentioned noun, as subject, direct object, indirect object, or object of a preposition; which, who.

   “I didn't see the car that hit me.”

adverb

1. To a given extent or degree. Denoting an equal degree.

   “Here's the measurement – the ribbon must be that long, no longer and no shorter.”

2. Denoting an equal degree.

   “Here's the measurement – the ribbon must be that long, no longer and no shorter.”

3. (Should we delete this sense?) Denoting 'as much', 'no less'.

   “She said we waited for three hours, but I'm sure it wasn't that long.”

4. To a great extent or degree; very, particularly.

   “I was seen quite quickly — I didn't have to wait that long.”

noun

1. Something being indicated that is there; one of those.