not

adverb5

1. •
   making a sentence mean the opposite, used with a verb such as "be", "do" or "can"

   • Did you take out the trash? — No, I did not. I do not think it was my turn, was it?
   • Not knowing any better, I went ahead.
2. •
   To no degree.

   • That is not red; it's green.
   • It's not you, it's me.
3. •
   Used to indicate the opposite or near opposite, often in a form of understatement.

   • That day was not the best day of my life. (meaning the day was bad or awful)
   • It was not my favorite movie of all time. (meaning the speaker dislikes or strongly dislikes the movie)
4. •
   Used before a determiner phrase, a pronominal phrase etc. to convey a negative attitude (e.g. denial, sadness, anger) towards something.

   • Oh god, not that! Anything but that!
   • Not another rainy day!
5. •
   (informal) Used before a non-finite clause (especially a gerund-participial clause) or less commonly a determiner phrase to ironically convey some attitude (e.g. surprise, incredulity, amusement, or embarrassment) towards something.

   • Not me writing example sentences again.

conjunction1

1. •
   And not.

   • I wanted a plate of shrimp, not a bucket of chicken.
   • He painted the car blue and black, not solid purple.

exclamation1

1. •
   (slang) Used to indicate that the previous phrase was meant sarcastically or ironically.

   • I really like hanging out with my little brother watching Barney … not!
   • Sure, you’re perfect the way you are … not!

noun2

1. •
   An instance of using the word “not”; a negation or denial.
2. •
   A unary operation on logical values that changes true to false, and false to true.

noun1

1. •
   Abbreviation of notice.

   • Mon. Not. R. Astron. Soc.