Incorrect spelling, explanation: necessary is an adjective form of the noun necessity. Thus, if it is: necessity + ary = necessary (we are replacing ending -ity, which is typical for noun, into -ary), it is mistaken to add one more c, and neccessary is an incorrect spelling.

Correct spelling, explanation: the word is created from the noun necessity, which means a strong need for something. Due to the spelling of the noun, we can’t add one more c to the adjective, and necessary is the correct form.

Definition of necessary:
adjective, something that is very much needed, had to be done to reach a particular effect. It can also be used in negatives, said to show disapproval about someone’s actions or words.
If you want to work in our company, good language skills are necessary.
Was it really necessary to yell? You should really work on controlling your temper.

Idioms and phrases with necessary:
→ necessary evil, the situation where we have to do something and accept it, even if we know it is morally wrong, usually for the sake of something important: Dozen of awful dates is necessary evil to find the one.
→ deem it necessary, to say that something is crucial: She deemed it necessary to go home when he wanted to stay.
→ the necessary, casual way to say money or any kind of income (what is interesting, it is also an old term meaning toilet or bathroom): I checked my account balance – looks like I still have some necessary.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling