In America, a 'pair of pants' refers to an item of clothing used to cover the entire lower torso and pelvic region of the body, but often also includes clothing that covers from the hip right down to the ankle. If the article of clothing doesn't cover the knees and below, it is usually referred to as 'shorts' or something, even though it's really still a pair of pants.
In England, a 'pair of pants' refers to an item of clothing used to cover the main areas of the lower region of the body (from hip down to just below the groin). Pants are usually covered (at least in public) with another article of clothing called 'trousers'. Trousers cover the body from below the torso to above the feet, and Americans call trousers pants.
What Americans refer to as 'shorts' or 'underwear' is actually a pair of pants to the British. Americans are much less specific in the definition than the British. In America, trousers are called pants and pants are called shorts or underpants. In Great Britain, underpants are called pants and pants are called trousers. British speaking people generally find this more amusing than American speaking people, who oftentimes don't understand why the Brits are laughing at them.
The Superman Comparative Example
Perhaps a good way to help both those of American English and the Queen's English visualise this entire condundrum properly is by way of the Superman Comparative Example.
In the UK, it is patently obvious that Superman does indeed wear his pants on the outside, when in hugely embarrassing superhero outfit mode; but to your avid American comic-book reader, it is patently obvious that Superman only wears pants on the outside when in Clark Kent mode.
In fact, while in Clark Kent mode, Superman's uniform functions as Clark Kent's underwear. Considering how Superman is such an icon of American culture, this may be the key as to why Americans are so ambivalent to the distinctions between underwear and outerwear.
Baggy Pants and Other Misnomers
Another difference between the American and English definition of this phenomenon is the phrase 'baggy pants'. In America, the phrase 'baggy pants' can be used to describe a particular style of wide-legged pants, often worn by skateboarders and snowboarders. Whereas, in England, the phrase 'baggy pants' can be used to describe a person with oversized buttocks (in relation to the national average).
In both America and Britain, the verb 'to pant' describes the action of heavy breathing, usually observed after an amount of rigorous exercise. Dogs are particularly renowned for their panting, due to the fact they don't sweat. The phrase 'baggy pants' is not often used in this situation.
In British playground slang, 'pants' can be utilised as both an insult or expletative. For example that television programme is pants and oh pants... I've lost my pencil. The phrase 'baggy pants' is a natural progression of the above in order to emphasise the point: that television programme is baggy pants and oh baggy pants... I've lost my pencil1.
This Guide Entry is PANTS, Man!
In America, a young person who audibly vocalised a phrase like, Man! That basketball game was so pants! will most possibly find their pants pulled up over their heads by their peers. The action of having one's under pants pulled up into one's scrotum while still in them is known as a 'Melvin' and is quite uncomfortable.
Though most Americans would not inherently be inclined to utilise the word 'pants' in this manner, if they were to consider it they would most probably begin using it as a more positive interjection or adjective, indicating excitement or more than casual interest. It's difficult to explain why, but has to do with the fact that overall, pants is actually a pretty exciting and versatile word. This, no doubt, would further amuse the occasional Englishman.
Instead of using pants as a negative expletative, young urban Americans would be more inclined to substitute 'pants' for words such as 'awesome', 'cool', or 'dah-bomb'. Other words such as 'tubular', 'radical', or 'wicked' were acceptable as little as a decade ago, but would nowadays possibly bring about a Melvin by one's peers. 'Dah-bomb' is already bringing about the potential for Melvins in much of the Pacific South-west.
This confusing use of the word 'pants' is in itself, inherently pants.
Besides the almost neurotic societal demands that everyone hidest thy nakedness, pants serve a more important purpose by taking the brunt of damage which otherwise would be reserved for the skin, were an individual to walk around au naturel.
Pants tolerate no end of abuses from weather, extreme heat and cold, spills of food, grease, grime, mud and muck, as well as the inevitable becoming entangled by anything from thorns to doorknobs2.
The most damaging place for a pair of pants, or any article of clothing, is the laundry. First, they sit for days in a hamper or a pile on the floor with other sweaty, smelling clothes. Then they are placed into two machines that would mean certain death for most anything living. They are bathed in chemicals and physically churned through the washer, and immediately thereafter go through a 'tumbling' process of extreme heat and friction, at which point they come out two sizes too small for the owner to wear.
The more damage a pair of pants withstands in service of its master, the poorer its condition. Human beings, of course, often take this for granted. Some even discard their pants at the first sign of wear and tear. They are either thrown away or given to one of many charities dedicated to finding used pairs of pants a good home. Other human beings cling to a trusty pair of pants regardless of their condition, wearing them practically every day and treating them like a long and dear friend or more naturally, an extension of the self. It is by what condition one's pants are in that aspects of one's character can be ascertained.
The condition of one's pants or trousers can be described in many ways, and most noticeably is dependent upon the care one takes in the pants themselves. Though there are many variants, the descriptions of the condition of pants generally falls into two categories: clean and unclean.
Clean pants are generally unwrinkled, properly pressed, and contain no holes whatsoever, except perhaps pockets in which various small objects can be collected and held for later use. It is important to note also that the volume of objects collected in one's pants can also affect the cleanliness. Large objects in pockets tend to cause unsightly bulges which make others wonder just what's going on under there. Clean pants rarely (if in fact ever) adversely affect the sense of smell. Either they smell divine, or have no smell at all.
Unclean pants are anywhere from slightly wrinkled to marvellously unkempt, containing massive bulges near the pockets and other areas. Stains are noticable and prevalent, as are holes, patches, frayed seams and an incorrigible smell which can be detected from a five metre radius about the wearer.
For reasons of hygiene it is recommended that pants are changed daily. However, lazy people can leave the same pair of pants on for many days, weeks, or even months before changing them; thus they become very smelly indeed.
Jeans vs Genes!
Less than a century ago it was not considered customary for women to purchase trousers unless they were buying them for a man. Today, almost as many American women wear trousers as men3.
English women don't wear slacks - it is really an American word. UK women wear jeans or trousers or leggings (which are those really clingy 'sports' sort of trousers) or track suit bottoms. Slacks do exist as a word for trousers in UK, but only really old ladies wear slacks. UK slacks are almost always chocolate brown, and always made of stay-press nylon. To say 'that's a nice pair of slacks you are wearing' to a woman in the UK would be taken as an insult.
However, regardless of the choice of wording that UK women use in regards to their pelvis/leg coverings, they're still pants from the American definition.
The reason American pants (and UK trousers) have gained popularity among women is because it is impossible to buy one trouser, or one pant. Pants always come in pairs, and in America, this led to what is now known as the Equal Rights Ammendment.
Trousers [or pants] are available two for the price of one, which automatically makes them the deal of the century for the addicted shopper. Though some women abhor the stereotype, women are arguably more prone to becoming addicted shoppers than men4, and when women realised that pants/trousers were perpetually ON SALE, there was no turning back.
Some historians believe the purchasing of pants by women for purposes of women wearing pants is directly proportional to the growing surge of the women's liberation movement of the past half century5.
Though females can wear trousers, they prefer to call them slacks, despite the fact that slacks are usually relatively tight. Tights are not related to slacks, but are a form of “trousered” stocking. Stockings and tights are also supplied in pairs and are generally worn by females.
Jeans are related to trousers in appearance, but are a paradoxical item of clothing. Originally manufactured from cheap cotton material known as denim, they were sold as an affordable, hard-wearing form of work clothing. Jeans have become fashionable items since their creation and, though still made from cheap cotton material, can cost more than a good pair of trousers.
Trousers and jeans have flies on them. This is not necessarily due to smells, stains etc., but is the term used for the convenient opening at the front (or for women, some slacks have this opening on the side). The fastening of this opening is achieved with buttons or zips and is mostly useful to male wearers.
The zip is the most preferred method, but careless, hurried closure can result in a particularly painful accident.
Trousers and jeans, depending on the current fashion trend, can be folded up at the ankle. This is known as a turn-up and can be used for storing many small items - paper clips, pins, dandruff, etc.
Strict dress codes apply to some occupations and professions regarding leg wear. For example, builders and road maintenance workers must have a considerably lowered waistband. Rock stars are often seen with leg wear that appears to have been applied with an aerosol can. This tight form of leg covering is particularly useful to the older rock star as an effective support for varicose veins.
Other Words For Pants
Trousers, jeans, denims, khakis, slacks, leggings, underwear, smalls, knickers, Y-fronts, boxers, briefs, thongs, stockings, panties... - sorry!6 That's enough.