Broad Rimes (Guangyun) pronunciation is na. Collected Rimes (Jiyun) and Collection of Rhymes (Yunhui) pronunciation is nan. The pronunciation is the same as the character meaning difficult. Explaining Characters and Writing (Shuowen Jiezi) defines it as: An-nu, meaning warm. Also, Collected Rimes (Jiyun) pronunciation is nian. The pronunciation is the same as the character meaning thus or so. Ye-nu, describing the appearance of warmth. Also, the pronunciation is na. The meaning is the same. Categorized Compilation (Leipian) notes it is sometimes written in a variant form.