It's impossible to say definitively who first used the word "environment" in the sense we understand it today. The word itself has a long history, dating back to the 14th century and originally referring to the surrounding circumstances or conditions of something.

However, the modern understanding of "environment" as the natural world and its impact on living things developed gradually over centuries.

Here are some key moments in the evolution of the word and its meaning:

* 14th Century: The word "environment" appears in English, initially referring to the surrounding circumstances of something, not necessarily the natural world.

* 18th Century: Scientists like Alexander von Humboldt started to study the interconnectedness of living organisms and their surroundings. This laid the groundwork for a more holistic view of the environment.

* 19th Century: The Industrial Revolution and its impact on the natural world raised awareness about the relationship between human activities and the environment. The concept of "ecology" as a scientific discipline also emerged during this period.

* 20th Century: The rise of environmental movements and growing concern about pollution, climate change, and resource depletion solidified the use of "environment" to describe the natural world and the impact of human activities on it.

Therefore, while there's no single person who can be credited with first using the word "environment" in its modern sense, the concept developed over centuries through the contributions of scientists, writers, and activists who recognized the interconnectedness of nature and human society.