Calidities is a rare term that refers to the quality or state of being warm or hot. There are several synonyms that can be used to replace this term, including heat, temperature, warmth, hotness, and fever. These words can be used in various contexts, such as to describe weather conditions, the temperature of a room or object, or the state of a person's health. Other similar terms that can be used include burning, scorching, fiery, torrid, sultry, and sweltering. It is important to choose the appropriate synonym depending on the intended meaning and context.