Active ingredient
Active ingredient means any substance (or group of structurally similar substances if specified by the Agency) that will prevent, destroy, repel or mitigate any pest, or that functions as a plant regulator, desiccant, or defoliant within the meaning of FIFRA sec. 2, except as provided in 174.3 of this chapter.
Source
40 CFR § 152.3
Scoping language
Terms used in this part have the same meaning as in the Act. In addition, the following terms have the meanings set forth in this section.