A forelimb is an anterior limb (arm, leg, or similar appendage) on a terrestrial vertebrate's body. For quadrupeds, the term foreleg is often used instead. (A forearm however is the part of the arm or forelimb between the elbow and the wrist.)
All vertebrate forelimbs are homologous, meaning that they all evolved from the same structures. For example, the flipper of a turtle or of a dolphin, the arm of a human, the foreleg of a horse, and the wings of both bats and birds are ultimately analogous, despite the large differences between them.