Correct spelling, explanation: the adverb thoroughly derives from the adjective thorough. As you can see, the spelling is quite difficult. That’s why some people tend to abbreviate it, likening this adverb to another word: through. We cannot do this! Remember to put the first -o vowel after the first -h letter. Throughly is just a mistake.

Definition of thoroughly:
adverb, in a thorough manner
You have to search your purse thoroughly to find your phone.
Read this book thoroughly before you say anything about it.

Incorrect spelling, explanation: the word throughly doesn’t exist since its root must be spelled with two -p. We have to remember to always look at the basic word, which in this case is the adjective thorough. To create an adverb, just add the suffix -ly to it and you’ll get the right form: thoroughly.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling