one of the large alphabetic characters used as the first letter in writing or printing proper names and sometimes for emphasis
"printers once kept the type for capitals and for small letters in separate cases; capitals were kept in the upper half of the type case and so became known as upper-case letters"
An upper-case letter (A, B, C, ... as opposed to a, b, c, ...), used for emphasis, for starting sentences and proper names, etc.