This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 晀 is uncertain. It visually combines 日 (sun/day) with 兆 (omen/sign), but the original semantic or phonetic role of these components is unclear.
The left side is 日 (sun), and the right side is 兆 (omen). Imagine a rare omen appearing in the sun, but its meaning remains unclear.
For チョウ, picture a long-serving chief named Chou staring at the sun, trying to interpret the omen: Chou -> チョウ.