steep slope
墹 centers on a steep slope or incline, often in the context of earth or terrain.
墹 combines 土 (earth) with 間, which likely contributes the sound and the idea of a space or gap, suggesting a gap in the earth such as a steep slope.
The earth radical 土 beside 間 (gap/space) creates an image of a gap in the earth: a steep slope or incline.
For まま, imagine a steep slope that a mother (まま, mama) carefully climbs, holding onto the earth: mama -> まま.
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