Meaning "equal":
* Equidistant: At equal distances from something.
* Equilateral: Having all sides equal in length.
* Equanimity: Mental calmness, composure, and evenness of temper, especially in a difficult situation.
* Equilibrium: A state of balance or stability.
* Equivocal: Open to more than one interpretation; ambiguous.
* Equivalent: Having the same value, amount, or effect as something else.
* Equal: Having the same quantity, size, degree, or value as another.
Meaning "horse":
* Equine: Relating to horses.
* Equestrian: Relating to horseback riding.
Other words:
* Equip: To provide with the necessary items for a particular purpose.
* Equipment: The tools, materials, or supplies needed for a particular activity or purpose.
* Equinox: The time of year when day and night are of equal length.
Note: The stem "equi-" can sometimes be spelled as "equ-" or "eque-" in some words, but it generally retains the "equi" form.