Correct spelling, explanation: names of the days of the week come from Old English and the literal meaning of Tuesday is the day of Tiw, who was a Germanic god of sky and war. Tuesday is the second day of the week that appears between Monday and Wednesday. Grammatically, it is a noun, but it can also function as an adverb. The plural form is Tuesdays. In English, we start the names of the week with a capital letter.

Definition of Tuesday
1. noun – a day of the week after Monday and before Wednesday,
Let’s go shopping together on Tuesday.

Expressions with Tuesday
Days of the week take the preposition on:
We can have a meeting on Tuesday.
When you use next or last with a day of the week, you don’t use a preposition: We can have a meeting next Tuesday.

Incorrect spelling, explanation: whenever there are two vowels next to each other in a word, there is also a probability of making a mistake in their order. Exactly that happens in the case of the word Tuesday, which is often mistakenly spelled as Teusday, which is incorrect so always pay attention to spell it right when you write it.