Greek Roots

4. cause to occur or operate at the same time or rate.
8. short for photoelectric cell.
9. (especially of a person) looking attractive in photographs or on film.
11. the branch of science concerned with the processes and phenomena of the atmosphere, especially as a means of forecasting the weather.
12. relating to geometry, or according to its methods.
13. an instrument on a vehicle's dashboard indicating its speed.
15. having or representing the earth as the center, as in former astronomical systems.
17. involving interaction between two different organisms living in close physical association.
18. a photographic copy of printed or written material produced by a process involving the action of light on a specially prepared surface.
19. (of an illness) persisting for a long time or constantly recurring.

1. the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms.
2. the quality of being made up of exactly similar parts facing each other or around an axis.
3. (of a record of events) starting with the earliest and following the order in which they occurred.
5. the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
6. the study of the physical features of the earth and its atmosphere, and of human activity as it affects and is affected by these, including the distribution of populations and resources, land use, and industries.
7. a numerical or other measurable factor forming one of a set that defines a system or sets the conditions of its operation.
10. the arrangement of events or dates in the order of their occurrence.
12. the science that deals with the earth's physical structure and substance, its history, and the processes that act on it.
14. a particle representing a quantum of light or other electromagnetic radiation.
16. an instrument for measuring the distance traveled by a vehicle.