百度和维式百科定义:

百度

爱情的定义就是：爱情是人们在恋爱阶段，渴求为所爱的人付出一些或全部所有的，并希望其永远幸福的感情思想。

wiki:

Love is any of a number of emotions related to a sense of strong affection[1] and attachment. The word love can refer to a variety of different feelings, states, and attitudes, ranging from generic pleasure ("I loved that meal") to intense interpersonal attraction ("I love my hu*****and"). This diversity of uses and meanings, combined with the complexity of the feelings involved, makes love unusually difficult to consistently define, even compared to other emotional states.

As an abstract concept, love usually refers to a deep, ineffable feeling of tenderly caring for another person. Even this limited conception of love, however, encompasses a wealth of different feelings, from the passionate desire and intimacy of romantic love to the nonsexual emotional closeness of familial and platonic love[2] to the profound oneness or devotion of religious love.[3] Love in its various forms acts as a major facilitator of interpersonal relationships and, owing to its central psychological importance, is one of the most common themes in the creative arts.