One of the sources of pronunciation of Japanese kanji
Kan'on is also a Japanese name for the goddess Guanyin.
Kan-on or kan'on (漢音, Japanese pronunciation:[kaꜜɰ̃.oɴ] or [kaɰ̃.oɴ], "Han sound") are Japanesekanji readings borrowed from Chinese during the Tang dynasty, from the 7th to the 9th centuries; a period which corresponds to the Japanese Nara period. They were introduced by, among others, envoys from Japanese missions to Tang China. Kan-on should not be confused with tō-on (唐音, Tang sound), which were later phonetic loans.
Kan'on partly displaced the earlier go-on, which were "just imitations of Korean imitations, but Kan-on were imitations of the real thing."[1]
A minority of characters never had their kan-on transmitted to Japan; their kan-on are sometimes reconstructed in Japanese dictionaries although not specifically marked as such. A few dictionaries go as far as to discard attested kan-on in favour of more systematic pronunciations.[1]