I've found this expression several times in my readings. As far as I'm concerned, it should mean something like "supposed, declared but actually not true". E.g.: «the alleged superiority of French team eventually turned into a bluff». Am I right? Thank you guys, any suggestion welcomed!

PS: how to pronounce it properly?
It can be true.
One alleges something to try to convince, to support in his/her own interest.
Hello Emotion: smile

"Alleged" means "stated or declared without proof or before finding proof".
So, your guess was partly right. It is similar to "supposed", but it doesn't necessarily mean that the "alleged superiority of the French team", to use your example, is not true. It may or may not be, and we will know that when/if evidence is found.
In your example, the superiority of the French team turned out to be false, but it might have been true as well (for example, if they had won the match -I take it you're talking about sports here).

I'm not sure I can help with the pronunciation because I find it difficult to do without the phonetic symbols, but I'll give it a try:
The "a" in alleged is pronounced like the "a" in "attempt", and the stress falls on the second syllable.
The secons syllable is pronounced "ledjshd"... you'll have to imagine that "djsh" is the sound of "J" in "John".

I hope it helps

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thank you very much elena and miriam! this was really useful!
You're most welcome Emotion: smile

its pronounced (uh-ledge-id)

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GuestPS: how to pronounce it properly?
I find this site useful for difficult words. Yes, shocking as it may be, even native speakers have trouble with some words. Emotion: smile
It's not perfect, it doesn't offer alternate pronunciations for example, but it's better than nothing. Just click the little speaker icon to hear the word.
A very frequent use of "alleged" is in a newpaper article describing someone who is accused of a crime, but has not yet been convicted in a trial. Here is a recent quote

A 20-year-old college student suspected of hacking into one of Alaska Gov. Sarah Palin's e-mail accounts was indicted Tuesday. He allegedly gained access to Palin's account by answering a set of security questions and changing the password. He then allegedly posted the new password online, enabling others to access the account.
how to pronounce allege
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