What is a woman? What is a man?
What prompted this submission, was the following from an AT article:
The clearly understood meaning of the word "woman" is a biological person with two x chromosomes. Presumably in an effort to avoid offense to the minuscule number of trans women who biologically are male (one x and one y chromosome) ...
Error! Too exclusive. Medically/scientifically too inaccurate. Not "clearly understood."
First, the correct definition, then the supporting argument.
A "woman" is an adult human whose karyotype includes one or more X chromosomes and no Y chromosomes.
As an added bonus, a "man" is an adult human whose karyotype includes one or more properly functioning Y chromosomes and one or more X chromosomes. There is no viable OY karyotype.
A doctor reviews the results of chromosome and DNA testing (public domain).
Here are your females (emphasis added):
1. XO — Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic condition in which a female is partially or completely missing an X chromosome. ... Turner syndrome occurs in between one in 2,000 and one in 5,000 females at birth.
2. XX — a person with a normal female karyotype, including two X chromosomes.
3. XXX — Triple X syndrome, also called trisomy X or 47. XXX is a genetic disorder that affects about 1 in 1,000 females. Females normally have two X chromosomes in all cells — one X chromosome from each parent. In triple X syndrome, a female has three X chromosomes.
4. XXXX — Tetrasomy X, also known as 48,XXXX, is a chromosomal disorder in which a female has four, rather than two, copies of the X chromosome.
Now for the boys (emphasis added):
1. XY — An individual with one X-chromosome and one Y-chromosome, the normal male karyotype.
2. XYY — XYY syndrome, also known as Jacobs syndrome, is an aneuploid genetic condition in which a male has an extra Y chromosome.
3. XXY — Klinefelter syndrome is a genetic condition in which a boy is born with an extra X chromosome.
4. XXYY — XXYY syndrome is a sex chromosome anomaly in which males have an extra X and Y chromosome.
...and a whole bunch more X and Y combinations leading to our last example of
5. XXXXY — 49,XXXXY syndrome is an extremely rare aneuploidic sex chromosomal abnormality. It occurs in approximately 1 out of 85,000 to 100,000 males.
Intersex is defined as follows: "Intersex is a group of conditions in which there is a discrepancy between the external genitals and the internal genitals (the testes and ovaries)."
A female can appear male when she is exposed in utero to excess male hormones. A male can appear female when he has a problem making, metabolizing, or using testosterone.
And, to revisit a point made earlier, where I qualified the Y chromosome with "properly functioning," a male can appear female or ambiguous when his Y chromosome fails to act like one. This occurs when a gene, called SRY, that lives on the Y chromosome, malfunctions or is absent. SRY "causes testes to form in the embryo and results in development of external and internal male genitalia. If there is a mutation in the SRY gene, the embryo will develop female genitalia despite having XY chromosomes." This is because SRY codes for a "protein (which) starts processes that cause a fetus to develop male gonads (testes) and prevent the development of female reproductive structures (uterus and fallopian tubes)."
So there you have it. A "woman" is an adult human whose karyotype includes one or more X chromosomes and no Y chromosomes. A "man" is an adult human whose karyotype includes one or more properly functioning Y chromosomes and one or more X chromosomes. There is no viable OY karyotype (though there might be an OYVAY phenotype).
99.9% of use cases covered.