Megapixel is a term used in digital imaging to quantify the resolution capacity of an image sensor. It represents one million pixels, with a higher number of megapixels generally correlating to a higher resolution image. In digital cameras, the megapixel count indicates the level of detail the camera can capture. However, it's essential to note that a higher number of megapixels does not always equate to better image quality, as factors like sensor size and quality also play a crucial role in determining the overall picture quality.