Not and knot are easily confused words. Not and knot are also homophones, because they are spelled differently, but sound exactly the same.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It suggests what word you may want to save time, but quite often, its suggestions couldn’t be more off base. Instead of being useful results, autocorrect produces humorous results.
Not is an adverb, it is used to modify verbs or adjectives to express the opposite, or the negative: for example not working versus working, not true versus true, not playing versus playing, not present versus present.
In slang, “not so much,” has become a catchphrase. It’s used as a criticism of what something isn’t, or the speaker’s lack of interest or enthusiasm about the topic: “I like movies, but writing term papers? Not so much. Did that VMAs outfit raise eyebrows? Yes. Was it flattering? Not so much.”
Knot is a noun. It means the result of rope, string, or other woven threads’ ends being crossed or looped one over the other, then the ends pulled to form a hard “ball” in the middle.
A knot can also be a tight, painful area in a person’s muscles that results from overuse. Massage usually help these situations.
Some idioms include knot. To “tie the knot” means to get married (hence a wedding magazine called “The Knot.”) To say you’re “in knots,” or your stomach is “in knots,” means you are stressing out about something, very nervous, or very anxious.
The following story uses both words correctly:
Natsu was an accomplished sailor. In interviews, he said it all started with tying knots on the docks when he was four, being fascinated by their interesting weaves and patterns. Sailing with his family every weekend was a tradition he would not miss for the world.