I know that diacritics are often retained in loanwords in formal writing (cf. naïveté ), but I haven't seen this done with direct adaptation of Latin words; i.e., per se . In Latin, per sē comes with a macron, indicating the longness of the vowel. This practice is uncommon (unused?) in English, but so are accents and diæresis marks, which are retained in the aforementioned naïveté . Is there any attested usage or relevant guideline regarding the adaptation of macrons from Latin? Answer In §11.94, Diacritics—specialized versus general contexts , the Chicago Manual of Style advises (emphasis mine): Nearly all systems of transliteration require diacritics—including macrons, underdots, and overdots, to name just a few. Except in linguistic studies or other highly specialized works, a system using as few diacritics as are needed to aid pronunciation is easier on readers, publisher, and author . ... For nonspecialized works, the transliterated forms without diacritics that are listed i...