1911 Encyclopædia Britannica, Volume 8… (1911)
“ The same form is also a title of honour in Portugal, as formerly in Brazil, used by members of the blood royal and others on whom it has been conferred by the sovereign. The Spanish form “don” is also a title, formerly applicable only to the nobility, and now one of courtesy and respect applied to any member of the better classes. The feminine form “donna” is similarly applied to a lady. ”
