默

Left component — 黑 is both the indexing radical and phonetic (hēi → mò, with significant drift but the rime preserved in older readings). 默 is to keep silent, to hold one's tongue darkly, and the 黑 anchors the 'darkness' image. The same phonetic drives 墨 mò (ink — black liquid), keeping the visual link between blackness and the mò-rime.

Dog on the right — a second semantic, supplying the original scene. 犬 is itself a stylised dog with a cocked tail. The traditional reading: a dog stalking silently at night in the dark — the source of 默 'silent'. The pairing fixes the picture, with the dog hushed under cover of 黑 (darkness).