edge forward, trample
躪 centers on forceful, invasive movement: edging forward aggressively or trampling over something. The two meanings share the idea of pressing forward with weight or disregard.
躪 is a phono-semantic compound: 足 (foot) suggests movement, and 藺 likely contributes the sound リン. The exact historical development of the right-side component is uncertain.
The left side 足 means foot. The right side 藺 looks like a dense, tangled plant. Imagine a foot pushing through thick undergrowth, trampling and edging forward.
For リン, picture a foot trampling a field of ring-shaped flowers: ring -> リン, and each step crushes the rings.