Double Spending - Meaning - Definition

[Mounty]

This the problem that the blockchain tried to resolve through the proof of work, sometimes it can be possible as a result of a 51% Attack, hack of the Blockchain which allows a coin/token to be spent more than ones.

More info about double spending:

[Chilwell]

Double Spending is a cryptocurrency network exploitation  where an individual Fraudulently attempt to use the same fund twice or duplicating the transactions. With the purpose of misleading the network into accepting duplicate transactions.