My "Concise Oxford Dictionary of English Etymology" says that 'holm(e)' was used in English meaning 'islet' in the 11th century and 'low-lying land by a river' in the 13th. As related words it gives 'holmr' from Old Norse meaning 'islet' or 'meadow by the shore', Old English 'holm' for billow, wave, sea (in poetic context), and Old Swedish 'holm' for 'hill'.

Robin