The best way to interpret these topics is to give an application. Your list is long therefore I've chosen a few due to enotes length requirements. You might want to split up your list of topics into additional questions.
Economics- the study of scarcity and choice. Application: you have $100.00 to spend but your choices add up to $200.00- instead of going home empty handed you could get something for your $100.00 by purchasing items you needed or wanted the most. Limited resources satisfying our unlimited wants.
Elasticity- is the change in the supply or demand for a product following a price change. Application: Demand- if a drop in price causes an increase in product demand it is 'elastic' if the drop has little effect the product is 'inelastic' Supply- as the price goes up on a product manufactures are willing to produce more of the product for sale.
Perfect Competition- for this market structure to exist there must be many buyers and sellers neither of which can be large enough to affect the price. Application: The production of eggs- there is very little an egg producer can do to differentiate his eggs from other eggs. Most consumers just check whether or not the eggs are broken before they buy them, thats all. Egg producers are 'price takers' (they have to take what they can get)
Monopolistic Competition- or imperfect competition- this structure holds that producers of similar products make them appear different. Application: Generic aspirin has the same exact chemical compound as 'Bayer' aspirin, however because of the 'reputation' 'Bayer' aspirin has gained through such venues as advertising there are consumers would believe that 'Bayer' is better although the products are almost identical. This application allows suppliers to have significant control over their prices, unlike the egg market.
Hope these applications are helpful.