生态学（德语：Ökologie），是德国生物学家恩斯特·海克尔于1866年定义的一个概念：生态学是研究生物体与其周围环境（包括非生物环境和生物环境）相互关系的科学。德语Ökologie（最初：Oecologie）是由希腊语词汇Οικοθ（家）和Λογοθ（学科）组成的，意思是“研究居住在同一自然环境中的动物（Lebewesen）的学科”，目前已经发展为“研究生物与其环境之间的相互关系的科学”。环境包括生物环境和非生物环境，生物环境是指生物物种之间和物种内部各个体之间的关系，非生物环境包括自然环境：土壤、岩石、水、空气、温度、湿度等。

In ecology, bionomics (Greek: bio = life; nomos = law) is the comprehensive study of an organism and its relation to its environment. As translated from the French word Bionomie, its first use in English was in the period of 1885-1890. Another way of expressing this word is the term currently referred to as "ecology". It is sometimes used as a subdiscipline of Ecological economics. An example of studies of this type is Richard B. Selander's Bionomics, Systematics and Phylogeny of Lytta, a Genus of Blister Beetles (Coleoptera, Meloidae), Illinois Biological Monographs: number 28, 1960. Michael Rothschild used the term in his book, but does not make reference to prior uses.