This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 窂 is uncertain. It visually combines 穴 (hole, cave) and 牛 (cow), but the original meaning and component relationship are unclear.
With no clear meaning, picture a cow (牛) stuck in a cave (穴) — an unusual scene that may help you remember the shape, but the meaning remains uncertain.
For ロウ, imagine a low (ロウ) cave where a cow is trapped: low -> ロウ, and the cow is in the cave.