1.
lid, cover, cap
A removable or hinged piece that covers an opening or container.
蓋 is a general-purpose word for any removable cover or lid on a container. It applies to pots, bottles, boxes, jars, and more.
Writing
The kanji 蓋 is common but hiragana ふた is also widely used, especially in casual writing.
Common expressions
蓋を開けてみないと分からない means "you won't know until you try" (literally, until you open the lid).
Similar words
Related Words
Related:
栓 (plug, stopper)
Compare:
キャップ (cap)
Compare:
カバー (cover)
Compare:
覆い (cover)