The word "coltishnesses" refers to a playful or energetic behavior, often associated with young horses. Some synonyms for this term include exuberance, friskiness, vivacity, and sprightliness. Other possible options might include spiritedness, liveliness, high-spiritedness, and playfulness. These words are all used to describe the same type of behavior, that of a creature or person who is full of youthful exuberance and energy. Whether you are describing a child running around on a playground, a puppy frolicking in the grass, or a young horse galloping across a field, these words will all convey the same sense of youthful playfulness and exuberance.