Define "pesticide" and its general use.

A pesticide is defined as a chemical substance specifically designed to kill, repel, or control pests, which include insects, weeds, fungi, and other organisms that can harm plants, crops, livestock, and humans. The primary purpose of pesticides is to protect crops and maintain agricultural productivity by managing pest populations that can negatively affect yield and quality.

This definition aligns with the role pesticides play in agriculture and pest management. While some substances may enhance plant growth or be classified as fertilizers, they do not serve the primary purpose of pest control. Moreover, using biological agents to promote pest populations is the opposite of what pesticides are intended to achieve. Therefore, the focus on the controlling or killing of pests is what accurately defines the function of pesticides and underscores their importance in agriculture and pest management strategies.