Q. AP style dictates that blonde (with an e) should be used only as a noun and I believe only for a female subject. Blond should be used as a noun for male subjects and as an adjective for both. I cannot find any reference in CMOS, but Merriam-Webster lists both spellings as variants for both nouns and adjectives. Is that Chicago’s position?
A. First, note that the AP Stylebook updated its advice in 2020, when its entry for “blond, blonde” was replaced with an entry for “blond” under “gender-neutral language.” (Subscribers to the AP Stylebook online can discover this by searching for “blond.”) The new entry continues to advise using blond for the adjective regardless of gender (the feminine e ending is from the French). But it advises against using either blond or blonde as a noun except in a direct quotation, advice that applies equally to brunette (which, however, is rarely spelled brunet).
Though CMOS doesn’t cover this topic, we like AP’s new guidance, which discourages writing that would reduce people to physical characteristics or gender stereotypes (as in a phrase like “the blonde in the front row”).
As for Merriam-Webster, Chicago usually prefers first-listed spellings over any variants; blond is the first-listed spelling for both the adjective and noun forms, so that’s what we’d prefer. The entry for “blond” in Merriam-Webster doesn’t currently (as of June 1, 2021) include a usage warning (cf. “broad,” which Merriam-Webster labels “slang, often offensive” as a synonym for “woman”). But AP’s advice suggests that it is best to be cautious when using either spelling as a noun.