Posted in Linguistic Annoyances at 22:50 on 14 March 2011
Yes, that is how you spell it.
It is not derived from the Latin for smallest, minimus, and hence should not be rendered as miniscule.
In my Shorter Oxford Dictionary its first definition is as a small letter in a 7th century cursive script. Secondarily it means lower case in general, then extremely small.
Its derivation is from French, after the Latin minuscula (littera), meaning minor letter.