Incorrect spelling, explanation: the word disappear is a derivative of the infinitive to disappear. As you can see, the prefix dis- has been added to the basis. Dis- is a negative prefix, it means not or none. When we add dis- to the beginning of a word, we give it the opposite meaning. You can’t change the spelling by putting an additional -s to it. Dissappear is just a plain mistake.

Definition of disappear:
verb, cease to be visible
My mother disappeared into the house.
They watched the train disappear into the distance.

Collocations with disappear:
Some most commonly used collocations include: disappear for good and disappear without a sound.
When I woke up, I realized that my father disappeared for good.
My ex-fiancé left me at the altar. He disappeared without a sound.

Correct spelling, explanation: disappear is a very common verb in the English language, as well as its root word – appear. As you can see, this word was created by adding the negative prefix dis- to the basis. You cannot change the spelling by putting a double -s here. Try to remember that the form disaappear is not correct.

Incorrect spelling

Incorrect spelling