English iron (and related forms in other Germanic languages) is a loanword from Celtic *īsarno- 'iron', whose origin is the IE adjective *H1ésH2r̥-no- 'bloody', derivated from *H1ésH2r̥- '(flowing) blood'.
Although nobody thought of it until now, *H1ésH2r̥-no- is also the origin of Spanish sarna 'scabies, mange', a pre-Romance word glossed by Latin authors. There're also Basque sarra 'rust, iron tartar'1 and Spanish sarro 'tartar, plaque', with assimilation -rn- > -rr-.
Although nobody thought of it until now, *H1ésH2r̥-no- is also the origin of Spanish sarna 'scabies, mange', a pre-Romance word glossed by Latin authors. There're also Basque sarra 'rust, iron tartar'1 and Spanish sarro 'tartar, plaque', with assimilation -rn- > -rr-.
The source of this and other loanwords is an IE substrate language called Italoid by the Indo-Europeanist Francisco Villar2 and Sorotaptic by the Catalan linguist Joan Coromines3. According to them, Italoid shares isoglosses with Baltic and Italic in the IE dialectal cloud.
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1 Only found in the Biscayan dialect, which also has sarna.
2 See Indoeuropeos y no indoeuropeos en la Hispania prerromana (2000).
3 Who has a quite different etymological proposal for this word.
2 See Indoeuropeos y no indoeuropeos en la Hispania prerromana (2000).
3 Who has a quite different etymological proposal for this word.
