FCN

A Fully Convolutional neural network (FCN) is a normal convolutional neural networks(CNN), where the last fully connected layer is substituted by another convolution layer with a large "receptive field". The idea is to capture the global context of the scene. See below figure:

Reference:
Long, J., Shelhamer, E., & Darrell, T. (2015). Fully convolutional networks for semantic segmentation. In Proceedings of the IEEE conference on computer vision and pattern recognition (pp. 3431-3440).