Words that begin with the letter U have a very general spelling/pronunciation pattern in common words, ignoring a few exceptions. First if the U is part of a prefix, use that sound. Most common initial U words use the prefixes UNI-, UN- or UP-. Second if there is no prefix, I will show you a spelling/pronunciation pattern to follow. Generally the prefixes support this pattern.
Long U at the beginning of a word is most commonly found in the prefix UNI-, as in unicorn, unicycle, uniform and university. But a short U is used in the prefix UN- as in undo, unhappy and unwind. A short U is also used in the prefix UP- as in upper, upstart and upturn. The root word use provides several words that begin with a long U sound, such as usable, useful, user and usual.
The general spelling/pronunciation pattern is that a word that begins with a U followed by two consonants will have a short U sound. For example: ulcer, umbrella and utter. If the word begins with a U and is followed by one consonant and then a vowel it will have a long U sound. For example: ukulele, ubiquity, utility and utensil. First pronounce the word according to the prefix. If the word has no prefix, follow this pattern to decide between a long or short U at the beginning of a word.
There are some special cases worth mentioning for the sake of completeness. A word that begins with a U followed by two consonants will sometimes have a schwa sound in some American varieties. (For simplicity, in this case, stick to UK English.) An initial U followed by R is a special case; it has a short UR blend as in urban and urgent or a long UR blend as in urine and Uranus. The pronunciations of the vowel-R blends vary and are a whole different topic. However for simplicity the general spelling/pronunciation pattern explained here will almost always be correct.
Previous articles covered other spelling patterns for long U. They included magic e and the digraphs EW and UE. This time I covered initial U. Unlike those other patterns, initial U does not often get pronounced with a long OO sound instead of a long U sound. Next time I will uncover a spelling pattern to separate long U and long OO.