Why does the word "LOSE" have the long U sound?
Welcome to the forums, Thomas.
There is often no explanation or logic behind English spelling or pronunciation. I've always wondered why there's a u in 'four' and 'fourteen' but not in 'forty'.
Nobody can tell me how that came about, and the mention of 'came' reminds of something else I wonder about: why is Cambridge on the River Cam pronounced 'Came-bridge' and not 'Cam-bridge'?
Don't look for the answer in the spelling - it is not there. 'Lose' has irregular spelling/pronunciation, so you just have to learn it.
If you really want to know 'why', then you have to look to the history of the English language - e.g. vowels changed from their original spellings, or printers made illogical decisions about spelling which became fixed.
A poem to illustrate the thread
Our Strange Lingo
When the English tongue we speak.
Why is break not rhymed with freak?
Will you tell me why it's true
We say sew but likewise few?
And the maker of the verse,
Cannot rhyme his horse with worse?
Beard is not the same as heard
Cord is different from word.
Cow is cow but low is low
Shoe is never rhymed with foe.
Think of hose, dose, and lose
And think of goose and yet with choose
Think of comb, tomb and bomb,
Doll and roll or home and some.
Since pay is rhymed with say
Why not paid with said I pray?
Think of blood, food and good.
Mould is not pronounced like could.
Wherefore done, but gone and lone -
Is there any reason known?
To sum up all, it seems to me
Sound and letters don't agree.
by Lord Cromer