- An organism (usually parasitic) capable of causing a disease in another organism (host).
- A plant that lives for more than two years, often for a number of years; many flower annually.
- The downward flow of water through soil and permeable rock formation to the ground water table.
- Any form of plant or animal life or any pathogenic agent that is injurious or potentially injurious to plants, animals, or their products.
- A quantitative expression of the degree of acidity or alcalinity of a solution.
- The study of periodic biological phenomena with relation to climate, particularly seasonal changes. These phenomena can be used to interpret local seasons and the climatic zones.
- The synthesis, by chlorophyll-containing plant or bacterial cells of organic compound (primarily carbohydrates) from carbon dioxide and a hydrogen source such as water. There is a simultaneous liberation of oxygen. The energy for the reaction is light energy in the form of photons.
- Water added to the surface of the Earth from the atmosphere. It may be either liquid (e.g., rain and dew) or solid (e.g., snow, frost, and hail).
- To alter the status of a business, industry, or land from public or government ownership or control to private ownership or control.
-To cut off or cut back part of a plant for better shape or more fruitful growth.