A dome is a shape that is half a sphere. One side of a dome is flat, and is the shape of a circle. If you turn a salad bowl upside down it is dome shaped. A dome made out of shapes that doesn't have a smooth surface is a geodesic dome.
Fis forFleur De Lis
A fleur de lis is a stylised lily flower. It is used on coats of arms, in jewellery, as a pattern on fabrics and tapestries and as a decorative element on many household objects. It is strongly associated with the medieval time period in England.
A form is the shape of something, or a framework made around the edge of an empty space that then is filled to make a shape. The picture is of some forms about to be filled with concrete to make the floor of a building.
A helix is a curve in three dimensions. The thread of a screw is a helix, and wire coiled around a rod makes a helix. A spiral staircase is a helix. Some plants, like in the picture, naturally grow into helixes.
The word "coil" is sometimes used to mean a helix and sometimes used to mean a spiral, or sometimes used to mean the act of wrapping something around something else to make a helix or spiral.
His forHemisphere
A hemisphere is half a sphere. The word hemisphere is usually used when talking about half of the sphere of the Earth, particularly the top and bottom halves of the sphere. The top half of the Earth is called the Northern Hemisphere and the bottom half is called the Southern Hemisphere.
A line is something thin that only goes in one direction (or one dimension), and has no corners. The sides of other shapes are drawn with lines. The picture is of lines painted on the floor of a railway station.