Chen Collection, Middle Volume. Radical: Tree (mù). Kangxi stroke count: 8. Page 513, Entry 13.
Tang Rhyme (Tangyun), Collection Rhymes (Jiyun), Rhyme Compendium (Yunhui), and Standard Rhymes (Zhengyun) state the pronunciation is gǎo. It is pronounced the same as gǎo (third tone).
Explanation in Discussion of Writing and Explanations of Characters (Shuowen Jiezi) states it means bright.
Book of Odes (Shijing), Odes of Wei, contains the phrase, The sun rises bright and clear.
Huainanzi (Huainanzi), Treatise on Astronomy, says that when the sun rises to the Fusang tree, it is called the beginning of dawn; therefore, the character is composed of sun placed above tree.
Jade Chapter (Yupian) defines it as high.
Guanzi (Guanzi), Inner Cultivation chapter, states, Bright as if ascending to heaven.
Collection Rhymes (Jiyun) also records the pronunciation as hào (third tone). The meaning is the same.