The term "Jackknife" refers to a type of folding knife that features a blade that can be folded into the handle. This design allows for safe storage and portability, making it a popular choice for outdoor activities like camping and fishing. The blade is typically secured in place when opened, preventing accidental closure during use. In addition to its use as a tool, "Jackknife" is also a statistical method used to estimate the accuracy of a model. This technique involves systematically leaving out one observation from a dataset and assessing the model's performance, helping to identify potential biases and improve predictions.