A natural penis is one which has not been altered
'uncircumcised' suggests that something has been omitted
which it hasn't
'intact' suggests that the circumcised version is damaged
which it isn't.
So we call it a 'natural' penis
The foreskin must be the most misunderstood part of the male anatomy. This is partly because circumcision at an early age has been common in all the English-speaking countries since the beginning of the twentieth century. In the USA it remains the normal choice, so many men and women rarely encounter foreskins.
What is a foreskin?
The penis has a shaft which is a tough piece of connective tissue (not muscle). At the head of the shaft is a heart-shaped knob, called the glans (from the latin word for acorn). The glans is covered with very delicate, silky-smooth skin, and contains the special nerve endings which are responsible for sexual sensations. The glans is the part which is - sometimes - covered by the foreskin or prepuce (the terms are interchangeable) in those men who have one. Inside both glans and shaft is spongy tissue, which fills with blood to make the penis erect. A common misconception is that the foreskin is just a single piece of skin which hangs over the glans. This is quite wrong. The foreskin is not in fact a distinct piece of skin at all, but just the excess of the loose skin which surrounds the shaft. This outer skin is attached at the base of the penis, where it joins the body. It is attached again below the glans, but elsewhere it is quite free, with hardly any connection to the shaft beneath. The skin is much longer than it needs to be just to cover the shaft. The surplus hangs in a fold over the knob, and this fold of excess skin is the foreskin.
This loose skin has three recognizably different parts. The part which covers the shaft continues quite unchanged over the outside of the glans. There is no way of saying where it changes from being the skin of the shaft and becomes foreskin - this boundary will vary with the weather, state of excitement and so on. At the tip, in front of the glans, is a constriction (a bit like a ring of elastic set into the skin) which is sometimes called the frenar band. This is often quite tight in a young boy, but in an adult man it may be barely noticeable, or even quite undetectable. This band serves to keep the fold in position over the knob, at least when the penis is soft. The skin beyond the constriction, which forms the inside of the fold and lies next to the sensitive glans, is rather thinner and softer, and tends to stay moist if the foreskin is worn forwards for most of the time. It remains moist - and keeps the glans moist - because it is very thin and its outer layer contains little or no keratin, the material which toughens and waterproofs the outer skin of the body. The skin of the glans does have a layer of keratin, and contrary to another popular myth this is identical in both circumcised and natural men. Both inner and outer foreskin are well provided with nerve endings, and quite sensitive to the touch, but these are only sensors for touch, pain, heat and cold and play no part in sexual response.
Whether the glans will be fully or partly covered, or have extra skin hanging in front of it, depends on how much loose skin there is, and how strong the 'elastic' in the constriction is. In a young boy the foreskin will normally cover the glans at all times, but it will usually be much shorter and looser in an adult man, uncovering the glans at least when erect.
When a man pulls back his foreskin, he just moves the loose skin backwards. Instead of folding over the knob, the extra skin now forms little wrinkles and rolls over the shaft. If he pulls it further the wrinkled inner skin will straighten out over the shaft, and the constriction will be anything up to half-way down it. The opening of the urethra, at the tip of the glans, is called the meatus. Just beneath it the skin is gathered up into a little web called the frenum or frenulum. The web usually does not hinder the smooth retraction of the foreskin, but it can sometimes be tight ('frenulum breve') and not allow the skin to be pulled back flush with the shaft. Frenulum breve can make intercourse uncomfortable or painful.
More about the foreskin:
Foreskins come in all shapes and sizes - some are long, some are short, some are tight, some are loose. Some cause all sorts of bother, others never give a moments trouble. If you have seen one, you certainly haven't seen them all.