In what year did Ernst Haeckel define the term ecology?

Ernst Haeckel defined the term ecology in 1866. He coined this term in his work "Generelle Morphologie der Organismen," which emphasizes the relationships between organisms and their environments. Haeckel's definition of ecology laid the groundwork for understanding how living organisms interact with one another and with their physical surroundings, which is fundamental to the field of biology. This historical context highlights Haeckel’s significant contribution to biological sciences, marking the formal establishment of ecology as a distinct scientific discipline. The other years mentioned do not align with Haeckel's introduction of the term, underscoring the importance of 1866 in the history of ecology.