The 25% rule is the maxim that local government's long-term debt should net exceed 25% of its budget. Debt beyond this range is considered a potential risk.
3D printing is an additive manufacturing process which creates a physical object from a digital design by depositing thin layers of material that is fused together. This process allows for the manufacturing of complex, one-off products.
51% refers to an attack on a blockchain by a group of miners controlling more than half a crypto-network's mining hashrate (computing power). This would allow attackers to prevent new transactions from gaining confirmations and being added to the blockchain, which would halt payments between some or all users. Attackers would be able to reverse transactions completed while there were in control, allowing them to double-spend coins.
The 52-week range is a data point used when reporting on individual stocks. The 52-week range includes the lowest and highest price the stock has seen during the previous 52 weeks.