This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 吂 is uncertain. It visually combines 亡 and 口, but the original component relationship is unclear.
With no clear meaning, picture a forgotten mouth (口) under a lost (亡) sign: the meaning is lost to time.
For ボウ, imagine a bow (ボウ) tied around the mouth (口) of a forgotten (亡) jar, sealing its unknown contents.