This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 媋 is uncertain. It visually combines 女 (woman) and 春 (spring), but the original meaning and component relationship are unclear.
With no clear meaning, focus on the shape: a woman 女 beside spring 春. Perhaps imagine a woman enjoying the beauty of spring, but treat this as a memory aid, not a definition.
For シュン, imagine a woman named Shun who loves spring: Shun -> シュン, and she stands beside the spring component 春.