Definition of knell. 1  transitive verb. : 2  to summon or announce by or as if by a knell. 3  intransitive verb. 4  1 : to ring especially for a death, funeral, or disaster : toll. 5  2 : to sound in an ominous manner or with an ominous effect.
For the journal, see Demography (journal) . Demography is the statistical study of populations, including of human beings. As a very general science, it can analyze any kind of dynamic living population, i.e., one that changes over time or space (see population dynamics).
A lepidopterist studies moths and butterflies. They are biologists or zoologists who specialize in the behavior or evolutionary history of various moth and butterfly species. Another name for someone who studies insects is an entomologist. They are often employed by universities and spend most of their time in a laboratory or in the field.