1580s, in the rhetorical sense (a chain of reasoning in graduating steps from weaker to stronger), from Late Latin climax (genitive climacis), from Greek klimax "propositions rising in effectiveness," literally "ladder," from root of klinein "to slope," from PIE root *klei- "to lean" (see lean (v.)).
The rhetorical meaning evolved in English through "series of steps by which a goal is achieved," to "escalating steps," to (1789) "high point of intensity or development," a usage credited by the OED to "popular ignorance." The meaning "sexual orgasm" is recorded by 1880 (also in terms such as climax of orgasm), said to have been promoted from c.1900 by birth-control pioneer Marie Stopes (1880-1958) and others as a more accessible word than orgasm (n.).
1835, "to reach the highest point," from climax (n.). Related: Climaxed; climaxing.
climax cli·max (klī'māks')
n.
The height of a disease; the stage of greatest severity.
See orgasm.
in ecology, the final stage of biotic succession attainable by a plant community in an area under the environmental conditions present at a particular time. For example, cleared forests in the eastern United States progress from fields, to old fields (with colonizing trees and shrubs), to forests of these early colonists, and finally to climax communities of longer-lived tree species. The species composition of the climax community remains the same because all the species present successfully reproduce themselves and invading species fail to gain a foothold. Because climatic changes, ecological processes, and evolutionary processes cause changes in the environment over very long periods of time, the climax stage is not completely permanent