Actinic refers to the quality of light that has higher energy and is more capable of causing chemical reactions. When the intensity of actinic light increases, it is described as being more actinic. Some synonyms for the phrase "more actinic" include higher energy, more potent, stronger, more intense, more powerful, and more effective. Considering actinic light's ability to cause chemical reactions, one could also use reactive or catalytic to describe light that is more actinic. In photography, the term "hard light" is often used to describe a more actinic light source that results in sharp highlights and shadows.