dust
壒 centers on fine, dry particles of earth: dust. The single given meaning is straightforward, with no major distinct senses to reconcile.
壒 combines 土 (earth) with 蓋, which likely contributes the sound and may relate to covering or a lid, suggesting earth particles that cover surfaces like dust.
The left side is earth 土, and the right side 蓋 looks like a lid covering a dish. Picture a lid lifted from a dish, releasing a cloud of fine dust from the dry earth.
For アイ, imagine an eye irritated by dust: eye -> アイ, and the dust from the earth makes your eye water.
Ainosho (dictionary of Buddhism, first published in 1446)