Wiktionary
n. A feature that distinguishes the two sexes of a species, but is not directly part of the reproductive system.
WordNet
n. the genetically determined sex characteristics that are not functionally necessary for reproduction (pitch of the voice and body hair and musculature) [syn: secondary sex character]
Wikipedia
Secondary sex characteristics are features that appear at sexual maturity in animals and during puberty in humans, especially the sexually dimorphic phenotypic traits that distinguish the sexes of a species, but that, unlike the sex organs, are not directly part of the reproductive system. They are believed to be the product of sexual selection for traits which display fitness, giving an individual an advantage over its rivals in courtship and aggressive interactions. They are distinguished from the primary sex characteristics — the sex organs — which are directly necessary for sexual reproduction to occur.
Well-known secondary sex characteristics include manes of male lions and long feathers of male peacock, the tusks of male narwhals, enlarged proboscises in male elephant seals and proboscis monkeys, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes, and these are often produced by a positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many species have brighter coloration or other external ornaments. Male jumping spiders have visual patches of UV reflectance, which are ornamentations used to attract females. Differences in size between sexes are also considered secondary sexual characteristics.
In humans, visible secondary sex characteristics include pubic hair, enlarged breasts of females and facial hair and adam's apple on males.
Usage examples of "secondary sex characteristic".
It was the same palpitating horror that at first he'd taken for a secondary sex characteristic in his original captors during that dizzy hegira through the monkey-puzzle forest and across the industrial plain.
Since a deep voice was not, on Ss'pode, a secondary sex characteristic of the male, the sex of casual acquaintances - and of public figures as well - could easily be disguised, and always was.
The talent came upon him without warning when he was twelve, as if it were a secondary sex characteristic accompanying puberty, manifested in modest ways at first, then increasingly strong and demanding.