Correct spelling, explanation: beautiful is the correct spelling because it is an adjective from the noun beauty, so when adding a suffix the y is changed to i. This is due to the fact that y is preceded by a consonant. In such a case, we change y to i when a suffix is added. The only exception is when a suffix starts with an i (like -ing). Another spelling problem in beautiful could be the suffix itself. There is an often mistake spelling where it is written beautifull (or even beautyfull if we include the previous mistake discussed). -ful however as a suffix is written with only one l, in contrast to the word full. Beautiful is therefore the correct form.

Definition of beautiful:
adjective, very attractive, pretty
My husband gave me beautiful red roses for our first anniversary.
Their new house is beautiful!

Incorrect spelling, explanation: there are two mistakes in beautyfull. First of all this adjective is made by combining the word beauty and suffix -ful. This suffix is always written with one l. The mistake with double l is most likely made because of the spelling of the word full. Thus, beautiful is correct. Another thing is that when we add a suffix to beauty y becomes i (this is because y in beauty is preceded by a consonant (there would be an exception in the case of a suffix beginning with i). Taking all of these things into consideration beautiful is the correct spelling.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling