tropism (n.)youdaoicibaDictYouDict[tropism 词源字典]
1899, "tendency of an animal or plant to turn or move in response to a stimulus," 1899, abstracted from geotropism or heliotropism, with the second element taken in an absolute sense; ultimately from Greek tropos "a turning" (see trope).[tropism etymology, tropism origin, 英语词源]