noun
: a natural or synthetic organic substance (as an auxin or maleic hydrazide) other than a nutrient that acts in very small amounts to modify any physiological process in plants — compare plant hormone
noun
: a natural or synthetic organic substance (as an auxin or maleic hydrazide) other than a nutrient that acts in very small amounts to modify any physiological process in plants — compare plant hormone
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012