Gelmir's name is not explained, and there are various possible sources. The initial Gel- might be from gyel-, 'triumph, joy' or from gal- 'bright'. Another potential origin is from the root ʒel-, 'sky blue', which matches well with the fact that Gelmir's brother Gwindor seems to have had gwind, 'pale blue' in his name. The final -mir is almost certainly 'jewel'.