double dagger (‡)
Definition - A printer's mark used to indicate footnotes.

Example -


1. Use it to indicate a third footnote when both an asterisk and an obelisk have already been used.

Oxford English Dictionary -
The term's first citation is from 1770:
"The Obelisk, or long Cross, erroneously called the single Dagger … The Double Dagger."
(Hist. Printing 259)

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