At least in North America, you would always refer to a unicorn. Here, words beginning with a vowel are preceded by an, but for some reason, words beginning with u are usually preceded by an a. read more
Best Answer: 'A unicorn' The only reason some think it should be "an" is that they were taught the rule incorrectly. The rule is NOT that you use "an" before a vowel, "a" before a consonant. It is that you use "an" before a vowel SOUND, "a" before a consonant SOUND. read more