覆 appears in many compounds: 覆盖 (to cover), 颠覆 (to subvert), 倾覆 (to capsize), 翻覆 (to overturn), 答覆/回覆 (to reply). The 'reply' meaning is more common in Taiwan and literary Chinese.
memory
Remember 覆水难收 (spilled water is hard to recover) — one of the most common proverbs using 覆. It's the Chinese equivalent of 'you can't put the toothpaste back in the tube.'
