Incorrect spelling


Incorrect spelling, explanation: idealy is an incorrect word form because it contains only one l. This would mean that the ending l of the root word ideal was cut out, or it would suggest that instead of -ly, only -y was added as a suffix. Both options are incorrect. This is why ideally is the only grammatically consistent and correct form.

Correct spelling


Correct spelling, explanation: ideally is the correct form as it contains the double l. One l comes from the stem word, ideal, the other from the adverb suffix -ly. When the suffix -ly is added to an adjective ending with an l, the letter is always doubled.

Definition of ideally:
1. if the conditions were perfect
2. flawlessly; to be perfectly suited for something,
Ideally, everyone in the country could access the Internet for free.
The sound of a piano fits ideally with the classy interior of this restaurant.