|1.||the sum of the characteristics that distinguish organisms on the basis of their reproductive function|
|2.||either of the two categories, male or female, into which organisms are placed on this basis|
|3.||short for sexual intercourse|
|4.||feelings or behaviour resulting from the urge to gratify the sexual instinct|
|5.||sexual matters in general|
|6.||of or concerning sexual matters: sex education; sex hygiene|
|7.||based on or arising from the difference between the sexes: sex discrimination|
|8.||(tr) to ascertain the sex of|
|[C14: from Latin sexus; compare secāre to divide]|
The property or quality by which organisms are classified as female or male on the basis of their reproductive organs and functions.
Either of the two divisions, designated female and male, of this classification.
Females or males considered as a group.
The condition or character of being female or male; the physiological, functional, and psychological differences that distinguish the female and the male.
The sexual urge or instinct as it manifests itself in behavior.
|sex (sěks) Pronunciation Key
Either of two divisions, male and female, into which most sexually reproducing organisms are grouped. Sex is usually determined by anatomy, the makeup of the sex chromosomes, and the type and amount of hormones produced. When the sex of an organism is determined by the sex chromosomes, males and females are generally produced in equal numbers. In other organisms, such as bees and wasps, in which females develop from fertilized eggs and males develop from unfertilized eggs, distribution of the sexes is unequal.
Our Living Language : Thanks to high school biology, we are accustomed to thinking of the sex of an organism as being determined by the chromosomes, notably the sex chromosome in humans (designated X or Y). But this is not the whole story, and it applies universally only to mammals and birds. In other animals sex is often determined by environmental factors and can be a variable phenomenon. In a species of slipper limpet (Crepidula fornicata), a kind of mollusk, all individuals begin life as females. Clinging to rocks and to each other, they form piles. The limpet on top of the pile changes into a male. If another limpet attaches itself on top of the male limpet, the newcomer becomes male, and the male limpet beneath it reverts to being female. These slipper limpets show the evolutionarily advanced feature of internal fertilization, and the male on top extends his reproductive organ down the pile of females below him to fertilize their eggs. For some fish, the number of males in the population determines the sex of the fish. If there are not enough males, some females become males. In these examples, the same animal can make fertile eggs and fertile sperm at different times in its life. These animals are not hermaphrodites, like some worms, but literally change sex. Some animals have only one sex. For instance, some species of lizards reproduce only by parthenogenesis—that is, their unfertilized eggs grow into adults, and these species no longer have males. Sometimes the external temperature determines the sex of an animal during its early development. If the eggs of the American alligator (Alligator mississippiensis) are incubated at above 34 degrees Celsius (93° F), all of the offspring become males. If they are incubated below 30 degrees Celsius (86° F), they become females. The midrange of temperatures results in both male and female offspring.