Fake Etymologies

Interesting is better than true.

stag‧nate, v. /ˈstægneɪt/

The Romans considered tin to be an alloy of silver and lead – specifically that the silver was debased by or contaminated by the lead. In the same way, water that did not flow would be contaminated by algae or made otherwise nonpotable. By metaphorical application, stagnum became “stagnant.”