Non-native speaker here. To me in spoken language both "unicorn" and "hour" have a combination of 2 vowels in the beginning. Let me transcribe them as "ee-oo" and "aa-oo" here.
Why is the aa-oo combination at the beginning of "hour" considered a vowel but the ee-oo in "uniform" is a consonant?
I didn't get the unicorn thing either, but it's explained better in the longer post (<a href="https://www.redblobgames.com/x/2635-a-vs-an/" rel="nofollow">https://www.redblobgames.com/x/2635-a-vs-an/). Unicorn is pronounced starting with a sound like 'you', which starts with a consonant.
mh-cx · · focus · HN ↗
Why is the aa-oo combination at the beginning of "hour" considered a vowel but the ee-oo in "uniform" is a consonant?
ryankrage77 · · focus · HN ↗