Epiphyte
A plant that grows upon another plant, but is neither parasitic on it nor rooted in the ground
Episome
A genetic extrachromosomal element (e.g., the fertility factor (F) in Escherichia coli) which replicates within a cell independently of the chromosome and is able to integrate into the host chromosome. The step of integration may be governed by a variety of factors and so the term episome has lost favour and been superseded by the wider term plasmid. Plasmids and F factors are episomes

Epitope
A specific chemical domain on an antigen that stimulates the production of, and is recognized by, an antibody. Each epitope on a molecule such as protein elicits the synthesis of a different antibody. a.k.a. antigenic determinant
Epizootic
A disease affecting a large number of animals simultaneously. equational division Mitotic-type division that is usually the second division in the meiotic sequence; somatic mitosis and the non-reductional division of meiosis. A chromosome division in which the two chromatids of each duplicated chromosome separate longitudinally, prior to being incorporated into two daughter nuclei