Kindly do not start a gender debate based on this question, but I am looking for words that are by definition gender-neutral, but (unlike 'actor' and 'nurse') are used to refer almost exclusively to persons of one gender.
Merriam-Webster online dictionary has been careful to define the following noun examples as 'a person who..., etc' and not as 'a man...' or 'a woman...' which leads me to consider them at least by definition gender-neutral nouns, though two of them appear to formally/formerly indicate gender, and a third (which is notorious) has a gender-specific equivalent:
Definition of watchman: a person who keeps watch : (syn) guard
Definition of midwife  a person who assists women in childbirth  one that helps to produce or bring forth something (help somebody to successfully complete some project, I assume, example: I am most indebted to my editor John, the midwife who delivered me of this most ambitious novel, etc.)
Definition of pimp: a criminal who is associated with, usually exerts control over, and lives off the earnings of one or more prostitutes (The female equivalent word with a very similar meaning is procuress, though its gender-neutral form is procurer)
Definition of janitor: one who keeps the premises of a building (such as an apartment or office) clean, tends the heating system, and makes minor repairs.
I am taking these only as random examples of gender-neutral nouns, of which I have heard watchman applied almost exclusively to men and midwife applied only to women. SIMILARLY, I have seen the word pimp applied only to men in my wide reading, and women who did something similar were often referred to as 'procuress'. I have myself heard 'janitor' used mainly for men, though I am sure there are many women janitors all over the world.
Other words such as washerman, policeman, seamstress and actress would be obviously gender-specific by structure, and probably applied only to persons of one gender, whereas words like 'actor' and 'nurse' which were previously used exclusively for men and women respectively have expanded to include all genders.
Unfortunately my imagination ends there.
So can you suggest any words in the modern language that are by structure and definition gender-neutral, but used to refer almost exclusively to people of one gender? Please note that these criteria will exclude words ending in -man (such as fisherman, chairman, fireman) because they are structurally gender-specific, even if they may be currently defined in a gender-neutral manner.
Note 2: is there any word that ends in -ess and formerly denoted women alone, which now refers to people of all genders?
Gender-related fact: are you friends at EL& U aware that non-Czech women's surnames are suffixed -ova in order to be made 'grammatically correct' in the Czech language?
AND in Slovak language as well!
(I am sure you know this, linguists and serious language enthusiasts that you are, but it is still something extraordinary, IMHO)