Correct spelling, explanation: the word grateful originates from the Latin gratus (meaning pleasing, agreeable) + -ful, morphologically it’s grate +‎ -ful. The adjective grateful comes from an obsolete adjective grate, meaning agreeable, thankful, which came from a Latin adjective, gratus, meaning pleasing. As you can see, it’s a derivative. You can’t change the spelling of its root. The only correct version is grateful, not greateful.

Definition of grateful:
adjective, showing or expressing thanks, especially to another person
I am grateful to you for helping me.
We will be grateful for whatever amount you can afford.

Collocations with grateful:
Some most commonly used collocations include: deeply grateful, eternally grateful, and truly grateful.
I am deeply grateful to you for your support.
I will be eternally grateful for what you have done for me.
I am truly grateful to my mother for raising me so well.

Incorrect spelling, explanation: you can’t write the word grateful as greateful, because the second version doesn’t exist, so it should be avoided. It doesn’t match the spelling of the root – grate. This error is probably due to pronunciation – great and grate sound the same. You need to be careful with this word. Grateful is the only correct form.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling