Solidus (Latin for "solid") may refer to:
* Solidus (coin), a Roman coin of nearly solid gold
* Solidus (punctuation), or slash, a punctuation mark
* Solidus (chemistry), the line on a phase diagram below which a substance is completely solid
* Solidus Snake, a character in ''Metal Gear Solid 2: Sons of Liberty''
* Solidus Labs, a cryptocurrency trade surveillance and risk monitoring company
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