...There are many possible definitions of emotional intelligence, and many definitions can be found on the Internet. Many of these definitions stem from the popularizations of emotional intelligence found in the popular press and in popular books...
A clear and scientifically useful definition of emotional intelligence, however, is recognizeable because it takes the terms emotion and intelligence seriously. That is, the meaning of emotional intelligence has something specific to do with the intelligent intersection of the emotions and thoughts. For example:
Emotional intelligence represents an ability to validly reason with emotions and to use emotions to enhance thought.
A more formal definition is...
We define EI as the capacity to reason about emotions, and of emotions to enhance thinking. It includes the abilities to accurately perceive emotions, to access and generate emotions so as to assist thought, to understand emotions and emotional knowledge, and to reflectively regulate emotions so as to promote emotional and intellectual growth (p. 197 of this article).
Here is another definition my colleagues and I have employed:
Emotional intelligence refers to an ability to recognize the meanings of emotion and their relationships, and to reason and problem-solve on the basis of them. Emotional intelligence is involved in the capacity to perceive emotions, assimilate emotion-related feelings, understand the information of those emotions, and manage them. (p. 267 of this article)
Emotion. In this model, emotion refers to a feeling state (including physiological responses and cognitions) that conveys information about relationships. For example, happiness is a feeling state that also conveys information about relationships -- typically, that one would like to join with others. Similarly, fear is a feeling state that corresponds to a relationship -- the urge to flee others.
Intelligence. In this model, intelligence refers to the capacity to reason validly about information.
This use of the term emotional intelligence in this fashion is consistent with scientific literature in the fields of intelligence, personality psychology, and emotions (for more, see the similar discussion in this article).
Verbal intelligence concerns the mental ability to reason with and about verbal information, and of verbal knowledge to enhance thought.
Spatial intelligence concerns the mental ability to reason with and about spatial information (i.e., the shape of objects and their orientation in space), and of spatial knowledge to enhance thought.
...and so on.
For more information about this conception of emotional intelligence, see the Four Branch Model of emotional intelligence.
For a comparison of this model to the more popular definitions, see How Does This Model Compare to Other Approaches....?
1. Mayer, J. D., Caruso, D., & Salovey, P. (1999). Emotional intelligence meets traditional standards for an intelligence. Intelligence, 27, 267-298.
2. Mayer, J. D., Salovey, P., & Caruso, D. R. (2000). Models of emotional intelligence. In R. J. Sternberg (Ed.). Handbook of Intelligence (pp. 396-420). Cambridge, England: Cambridge University Press.