滞后
zhì hoù · HSK 7
to lag behind
🐌 滞 stagnant + 后 behind = stuck behind = to lag behind
滞 means stagnant or sluggish flow; 后 means behind or after. Together they name something that trails the rest because it moves too slowly to keep pace.
后 — 厂 cliff + 一 + 口 mouth
Originally depicted a ruler or sovereign issuing commands, showing a figure with a mouth giving orders. It came to mean 'queen' or 'empress.' In modern simplified Chinese, 后 also absorbed the meaning 'behind/after' from the traditional character 後, so context decides which sense applies.