White-letter is a typographical term refering to the slender typefaces popularized by Romanesque printers. White-letter (also sometimes unhypehnated) includes Roman and Italic letterforms. Originally, white-letter typefaces were based on the chancery style of handwritten Latin manuscripts.
The term 'white-letter' refers to the sparse appearance of the printed page set in a white-letter type. It's counterpart is black-letter.
Garamond, found in many collections of computer fonts, is one of many examples of white-face type.