An agent that is used to stimulate one's sexual urges, desires, usually chemical in nature, or to improve one's attractiveness.
The use of food, drugs, or behavior patterns, rituals, one uses to improve or increase their sexual desires, their attractiveness to others, in a purely sexual way.
The ingestion of certain foods, such as Chocolate, Strawberries, Oysters, have been popular foods associated with also being aphrodisiacs, though no real evidence exists to prove or disprove such claims.
Mostly, aphrodisiacs, are a myth, that people may actually believe, due to their own mental process which attributes certain events to their use of such drugs, objects.
Behavior patterns may be the rubbing of a Rhino Horn, wearing an amulet with a Rhino Horn, or Tiger Penis. These myths assume a transference of sexual prowess, stamina, from the animal to the person touching or wearing the symbol.
Taken from the Greek Goddess Aphrodite, who was the Goddess of Sensuality, of Love.
From a purely scientific standing, there is no direct evidence of any drug or food that actually does improve one's sexual drive, or desire. However, there is ample evidence that it could be a result of association or of belief.
That being that an item may have a shape, scent, that one associates with sex, or sexual prowess, which triggers a mental response for the release of certain chemical in the body.
Some may simply be willing to believe in the legend of an item, thus ingesting or using a particular item may make them believe it will help their desire, and does, though it is more of a result of their belief, than the item itself.
The shape of the oyster for example, or the Rhino Horn, may be powerful aphrodisiacs, simply due to their legend, or mystical powers. Same holds true for the penis of a Tiger. It can also be due to their shape, which conjures up sympathetic associations, say with a penis.
This type of belief, or legend is considered to be 'sympathetic magic' and in fact has placed both the Rhino and Tiger into danger, due to the unfounded belief.
The belief is generally based on the animals aggressive nature, or sexual prowess in the species, so the belief being that a particular part of their body will enhance a human's sexual desire.
History (Legend): Without any valid evidence to prove it, no food, object, or chemical can be considered to actually have a direct effect on one's libido.
On the other hand, many claim results, which is explained as being more of a mental belief that the aphrodisiac works.
Ingestion of Chocolate for example, is believed to release added chemicals in the Brain, that increase sexual desire, arousal, however it is mostly believed that such a release is minimal or not long lasting to actually have any real effect.
Varied due to the different type of items people will consider to be aphrodisiacs.
Ingesting large quantities of Oysters for example a few hours prior to engaging in sex, is believed to improve a man's stamina, to keep them harder, than they normally would.
There is no medical / scientific proof of this.
Wearing various salves, creams, are believed to also improve one's sexual prowess, though again there is no evidence to prove, or totally disprove these claims.
In some instances, there can be momentary improvement of blood circulation or tenderness, that can account for the claims, but there is no evidence of any long term or long lasting benefits.
Practice (Associated Acts): Certain Drugs are believed to allow for an increase in one's sexual desire, however they also reduce a person's ability to actually perform. These drugs, such as Cocaine, Crystal Meth, can impair one's sexual abilities if used over any length of time.
They are stimulants, that release certain chemicals in the brain, that may trigger sexual desire, increased sexual playfulness, but they also pose serious health and judgment risks.
Noteworthy: Drugs like Viagra and Livitra are not aphrodisiacs, even though they do effect one's sexual ability. Some may belief they are, for that reason, that it allows them the ability to engage in sex for longer times. However, they do not effect the brain, or create a chemical reaction in the brain, which is what most Aphrodisiacs are purported to do.
Some foods or drugs do release chemicals that can mentally arouse a person, though in minute amounts. There is no definitive proof of any long term benefit, or even if the minimal benefit is of any consequence.
Some drugs, that can improve a person's blood flow, can be construed as being Aphrodisiacs for that simple reason. By improving the blood flow to the penis, an erection becomes easier to attain, and maintain, hence the belief they are actually aphrodisiacs.
Drugs such as Cannabis or Alcohol are not aphrodisiacs, but are more likely to decrease one's inhibitions, which can lead to improved sexual desires. As it does not directly improve one's desire for sex, it can't be classed as an aphrodisiac.