Estrual refers to a state relating to or indicating estrus, which is the period of sexual receptivity or fertility in female mammals. Some synonymous terms for estrual can include estrous, in heat, or receptive. Other similar words include proestrus, which is the period before full estrus, and diestrus, which is the period after estrus. Additionally, the term estrus can be substituted for estrual, as they are closely related concepts. These words are commonly used in the context of animal breeding, particularly with livestock such as cows, horses, and pigs. Understanding the synonyms for estrual can broaden your knowledge of the reproductive behaviors of different species.