A dryad (/ˈdraɪ.æd/; Greek: Δρυάδες, sing. Δρυάς) is a tree nymph or tree spirit in Greek mythology; Drys (δρῦς) signifies "oak" in Greek. Dryads were originally considered the nymphs of oak trees specifically, but the term has evolved towards tree nymphs in general.[1] Often their life force was connected to the tree in which they resided and they were usually found in sacred groves of the gods.[citation needed] They were considered to be very shy creatures except around the goddess Artemis, who was known to be a friend to most nymphs.