N. Boromir m.
Earlier name of Borlach (LR/134). In The Etymologies, it was given as a derivative of ON. Boronmīro (Ety/BOR). The medial [m] developed from [mm] < [n+m], which is why it did not become [v]. This is a distinct etymology of the later name of S. Boromir of Gondor, where the medial [m] was explained by the fact that it was a mixture of Sindarin and Quenya elements.
References ✧ Ety/BOR; LRI; WJI/Boromir¹
|ON. Boronmíro/Borommíro > Boromir||[boronmiro] > [borommiro] > [borommir] > [borommir] > [boromir]||✧ Ety/BOR|