Oh yes, words are infinitely flexible, and are to be used playfully and creatively...
...except, of course, when they're not.
Now, the clue to this word is at the beginning, okay? - the uni bit.
Think unicycle, unicorn, and uniform.
Or, indeed, think of a unicycling unicorn wearing a uniform: I should imagine you will be one of the first people ever to do so.
What you won't be, though, is almost unique.
If something is unique means there's only one of them. That's all it means.
Yes, yes, people will say almost unique, meaning very unusual, but this is bad bad BAD because nice knobbly awkward words which have just one meaning, like unique, are actually quite unusual and we should cherish them like mad and not try to rub the corners off them, because that's cruel as well as wasteful, and knocks a colour out of the gorgeous language rainbow.
Probably a sort of charcoal grey, I should say.
Word To Use Properly Today: unique. This word comes from the Latin word ūnicus which means unparalleled, from ūnus, which means one.
This means that uni has meant one for thousands of years, so please don't go and spoil it now, okay?