| poppleton | |
| appleton |
| appleton | (n) English physicist remembered for his studies of the ionosphere (1892-1966), Syn. Sir Edward Victor Appleton, Edward Appleton |
| appleton | (n) a town in eastern Wisconsin |
| appleton layer | (n) the highest region of the ionosphere (from 90 to 600 miles up) which contains the highest concentration of free electrons and is most useful for long-range radio transmission, Syn. F region, F layer |