Holm, n. (also holme) Brit.
1 an islet, esp. in a river or near a mainland.
2 a piece of flat ground by a river, which is submerged in time of flood.
Holm, n. (in full holm-oak) an evergreen oak, Quercus ilex, with holly-like young leaves.
ME alt. of obs. holin (as HOLLY)