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mark; sign
symbol; emblem
badge; crest; flag
evidence; proof
token (of gratitude, affection, etc.)
「証」 has other readings with different meanings.
友情の証として指輪を交換した。
We exchanged rings as a sign of friendship.
これが彼の無実を示す証となるだろう。
This will serve as proof of his innocence.
感謝の証として贈り物をした。
I gave a gift as a token of gratitude.