A hawk is a relatively large bird that hunts small animals. Hawks tend to surprise their prey, swooping down on it from above.
Among birds of prey, hawks are medium-sized, with long tails and curved wings. Hawks use their high intelligence and sharp eyes for hunting smaller birds and mammals. You can also use the word hawk to mean a pro-war politician or political advisor, a term that's often contrasted with "dove," someone who almost always opposes war. This metaphorical hawk has been around since the 1960s.