This flashcard defines "deer" as a noun referring to a large, wild animal with long legs that eats grass and leaves, known for its speed and males often having branching horns.
[N-COUNT 可数名词]鹿 A deer is a large wild animal that eats grass and leaves. A male deer usually has large, branching horns.
Oxford
deer/dɪə(r); NAmEdɪr/noun(pluraldeer)an animal with long legs, that eats grass, leaves, etc. and can run fast. Most male deerhave antlers(= horns shaped like branches). There are many types of deer.鹿◆a herd of deer一群鹿◆a deer park鹿苑☞see also