holm comes from Old Norse holmr ('islet, small island'), reinforcing Old English holm ('sea, wave, mound'), both from Proto-Germanic *hulmaz ('rising ground, islet'). The path is chiefly one of transmission: the word passes through the named languages and forms, with each stage preserving part of the modern shape. In present English, the noun sense is "a small island in a river or lake, or low flat ground beside a river", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as holmgang. Its semantic neighborhood includes islet, ait, eyot, and island, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Old Norse holmr and Proto-Germanic *hulmaz.