Correct spelling

referred

Correct spelling, explanation: the verb refer is a two-syllable word with the second syllable stressed (reFER), ending with a combination consonant-vowel-consonant. In such cases we double the last consonant when adding ending -ed (referreferred). Therefore referred is the correct spelling and refered is wrong.

Definition of refered:
verb, past simple and past participle form of refer; to mention or call something/someone in certain way; in medical language to send patient to specialist or some treatment
He referred to me as “Mrs Jones” although I asked him to call me by my first name.
The patient was referred to blood test.


Incorrect spelling

refered

Incorrect spelling, explanation: refered is an incorrect form, because r at the end should be doubled. We double the last consonant when adding suffix -ed when a two-syllable word has stress on second syllable (reFER). Therefore the correct form of this word is referred – with the last consonant doubled.

Incorrect spelling

reffered

Incorrect spelling