Glyph apparently was a round shape a long time ago, as is the SUN, perhaps as the pundits believe depicting something halfway above and below the horizon. May also be「two stacked orifices」with a wall as separator, FLASHING, BRILLIANT, SHINING but unable to look at very long without permanently damaging one's eyesight by scarring internal tissue of the retina.
　Often used in many textual situations interchangeably with 'tonguing mouth, rod in orifce' (曰) for what occurred at dawn with all those morning erections of woody (or as it is formally known, nocturnal penile tumescence, NPT), just as Moon (月) is used interchangeably with meat (⺼) for what occurred in the early evening…and what does a hot, sunny day make one do other than open one's mouth showing tongue and panting due to the heat? with humans being not unlike dogs in that regard when confronting「two stacked orifices」?
　Combined with 'prick head' to mean 'star' (星) and in other 'heavenly body' glyphs, depicts the worship and religion espoused by the first shamans, that of the sale or short-term rental of divine sexual service providers for profit:「two orifices stacked on head of prick.」
　Also used as an abbreviation for JAPAN. The assignment of the two glyphs 曰 and 本 to represent Japan was done by the Chinese, and was NOT a Japanese idea. Now, who honestly believes that the Chinese were suddenly trying to be kind to the Japanese by doing so? The original glyph that the Chinese assigned to represent Japan was 倭, which means literally:「people with short legs bent over and stooping like rice-planting women」a「person who shifts blame, or, only works by committees of women」and means「dwarves, the short people, stooped, lame and sprained, bent over and bowing all the time.」
　Subsequent Chinese usage referring to Japan as the so-called Land of the Rising Sun was also intended as a pejorative, and was not complimentary. Quote:
　Both Nippon and Nihon literally mean「the Sun's origin」that is, where the sun originates, and are often translated as the Land of the Rising Sun. This nomenclature comes from Imperial correspondence with Chinese Sui Dynasty and refers to Japan's eastward position relative to China.
　[Pause quote: Not likely though—the Chinese were not that stupid, and they did not believe that the Sun rose from land in Japan or anywhere on Earth, but they thought perhaps the Japanese could be spoofed with flattery—the title of Land of the Rising Sunwas simply another disguised insult, easily accepted by the Japanese who from antiquity have worshipped the Sun as their god Amaterasu. According to Japanese legend, this god, or goddess (its sex is uncertain), sealed itself inside a cave. Please, think about that for a while. This whole idea was merely another Chinese insult describing Japanese as cocksuckers:「tonguing mouth with woody shaft」]
　Continuing the quote: Before 'Nihon' came into official use, Japan was known as Wa (倭) or Wakoku (倭国)…[as] shameful (writing Japanese Wa as 倭 implying「dwarf」), and summarizes interpretations for ʼWâ「Japanese」into variations on two etymologies:「behaviorally 'submissive' or physically 'short.'.」…Examples include「Respect is shown by squatting」(Hou Han Shu, tr. Tsunoda 1951:2), and「they either squat or kneel, with both hands on the ground. This is the way they show respect.」(Wei Zhi, tr. Tsunoda 1951:13) …The second etymology of wō 倭 meaning「dwarf, short person」has possible cognates in ǎi 矮「Short person. Midget, dwarf. Low. wō 踒 Strain. Sprain. Bent legs, and wò」臥「Lie down. Crouch. Sit (used for animals and birds). Chinese, Korean, and Japanese scribes regularly wrote Wa or Yamato「Japan」with the Chinese character 倭 until the 8th century, when the Japanese found fault with it, replacing it with 和」
　　[　https://en.wikipedia.org/wiki/Names_of_Japan 2012-08-09　]　
　So, it required no less than 600 years for Japan to recognize that the Chinese were ridiculing them as submissive crouching dwarves who squat like women and animals. Incredibly, the glyphs 曰 and 本 (not 日 'Sun'), the next name assigned to Japan by the Chinese, are still often seen in Japan written as 曰 tonguing mouth on 本 woody shaft. To say the least, the Chinese at that time were not pleased with the Japanese ambassadors who had arrived to complain about the previous name assigned to Japan of「submissive crouching dwarves who squat like animals and women (倭)」or the replacement「mouth orifice with head of woody (和)」and were keen to spoof the Japanese again, besting their forebears, eagerly explaining with just slightly more subtlety than was used 600 years prior that from the Chinese perspective, Japan is the land from which the Sun rises every day, all the while knowing that the meaning of the characters given to the Japanese emissaries meant tonguing mouth on main shaft of a woody, the same idea behind 和. It is not the least bit difficult to imagine that 1,200 years ago the Chinese would have attempted this…however, what is a wonder is that the Chinese could explain all this while keeping a straight face and not falling over laughing their asses off. Another glyph that the Chinese assigned to Japan and Korea, 龺, meaning「imbeciles, people who believe the Sun rises from land [as the goddess or god Amaterasu] out of the Earth's horizon.」…see that glyph for details, but remember that not too long ago most Europeans believed that the Earth was flat and dragons lurked at the edges, or, that the Earth was the center of the solar system and the Sun and Moon orbited the Earth (the Catholic pope executed folks for thinking differently). Today, most relatively intelligent folks believe that the Earth orbits the Sun, and the Moon orbits the Earth, but the existence of dragons is still a coin toss, with the flat-Earthers in a class unto themselves.
　Perhaps it is time that the Japanese looked into a different writing system and replace the use of kanji, although after 2,000 years, this is not likely to happen, and although Mao Zedong himself suggested China cease using kanji for writing way back in 1955, endorsing「basic reform」involving a transition from Chinese characters to alphabetics. He failed to pursuade then, but this could be done today with the technology now available that Mao didn't have access to in 1955.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: sun; day; date, day of the month; abbr. for 日本, Japan
Japanese: day of month, counter for days, Sunday, Japan, sun, sunshine, sunlight, case, event, every day, daily, day after day, by the day, twilight, sunset, dusk, evening, normally, habitually, rays of the sun, fixed date, appointed day, sunny place, in the sun, the number of days, sunshade, blind, exposure to the sun, high noon, sunny spot, rip-off-a-page calendar, daily pad calendar
Unihan extended: sun; day; daytime
EDRDG: day; sun; Japan; counter for days

Used within names (nanori)
あ　･　あき　･　いる　･　く　･　くさ　･　こう　･　す　･　たち　･　に　･　にっ　･　につ　･　へ