I was going to say "avuncular" but apparently not:

#6 -- No, I'm the one who didn't read OP carefully.
So we've got:
harlot, whore, floozy, tramp and slattern, and maybe slut (I disagree with you about prostitute and maybe about whore and tramp);
the feminine-specific professions, which no longer have a masculine-specific counterpart;
drake, bull, bitch;
pederast, catamite, geezer, stud, eunuch.
Are there female curmudgeons?
Can a male be a smart cookie? (If anyone can be a smart cookie any more.)
There are some adjectives that seem always to go with one gender, usually female: shrill, feisty, etc. But that probably is another topic.
There are some adjectives that seem always to go with one gender, usually female: shrill, feisty, etc. But that probably is another topic.
Buxom, busty, but barren was she.
Easy peasy.
Oops I am confusing tonight. It was slut I thought was gender specific due to the intent or feeling behind the usage of the word. It is why I wasn't too sure myself if the word itself would count - after all, intent varies. But I can't think of whenever I have heard someone say 'slut' without almost passing a moral judgement on the person.
I would imagine that prostitute was either gender neutral - although perhaps mostly female - but even if it wasn't would be 'matched' with gigalo.
Edited by: sneaker_fish
I didn't realise smart cookie was gender specific either!
I definitely can't think of a feminine counterpart to curmudgeon.
The word “God” or “He”.
“Orgasm”. I’m fairly certain there is no known female equivalent.

There is also 'lesbian' - a homosexual woman. There is no commonly used term for a gay man except 'gay man'.
I suspect there are other words related to same sex relationships that are gender specific.
I found an archaic female equivalent of cuckold.+ It's +cuckquean. "In the 16 and 17 th centuries, the wife of an unfaithful husband." It's in the OED.
Heywood, Proverbs 1562 "Ye make hir a cookquean."
Joyce used it in Ulysses:
A wandering crone, lowly form of an immortal serving her conqueror and her gay
betrayer, their common cuckquean
“Orgasm”. I’m fairly certain there is no known female equivalent.
The feminine of "orgasm" is "orgasm." In other words, this is a gender-neutral term. Unless you are being ironic.
A spinster is a single elderly woman. I can't think of a term for a single elderly man.
A spinster was actually a women who had passed the usual marriage age, but was still single. That didn't necessarily make her elderly. In Little Women, published in 1869, the heroine laments on the eve of her 25th birthday
>"An old maid, that's what I 'm to be. A literary spinster, with a pen for a spouse, a family of stories for children, and twenty years hence a morsel of fame..."
The author goes on to moralize:
>At twenty-five, girls begin to talk about being old maids, but secretly resolve that they never will be ; at thirty they say nothing about it, but quietly accept the fact, and, if sensible, console themselves by remembering that they have twenty more useful, happy years, in which they may be learning to grow old gracefully.
"Confirmed bachelor" used to be the term used for an old guy who never married, but it was also a euphemism for homosexual.
AH, here's the OED entry
'cuckquean, sb. Obs. Forms: 6 cook-, 6-7 cock-, cuc-, 7 cuck(e-; also 6 cut-, 7 quot-.
Etymology: f. stem of cuck-old + quean.
A female cuckold.
1562 J. Heywood Prov. & Epigr. (1867) 62 - Ye make hir a cookqueane.
1565 Golding Ovid's Met. vi. (1593) 146 - Queene Progne was a cutqueane made by meanes of her.
1614 Sco. Venus (1876) 39 - That hast made her a quot-queane shamefully.
1615 Heywood Foure Prentises Wks. 1874 II. 216 - Hee'd make his wife a Cucke-queane.
A. 1652 Brome City Wit iv. i, - To bee made Cuckqueane by such a Cockscombe.
1922 Joyce Ulysses 15 - A wandering crone..their common cuckquean.
Hence 'cuckquean v. trans., to make a cuckquean of.
1592 Warner Alb. Eng. viii. xli. (1612) 199 - Came I from France..to be Cuckquean'd heere?
A. 1652 Brome Mad Couple iii. i, - You can doe him no wrong..to cuckold him, for assure your selfe hee cuckqueans you.