all you need is love.

Wikipedia:
Love is any of a number of emotions related to a sense of strong attachment and affection.

Dictionary.com:

Love is a profoundly tender affection for another person.

Love is a feeling of warm, personal attachment and deep affection, as for a parent, child or friend.

Love is a sexual passion or desire.

Love is a person toward whom love is felt; beloved person; sweetheart.

Love is affectionate concern for the well-being of others

Love is a strong predilection, enthusiasm, or liking for anything.

To love is to have love or affection for.

To love is to have a profoundly tender, passionate affection for.

To love is to have a strong liking for; take great pleasure in.

To love is to need or require; benefit greatly from.

To love is to embrace and kiss (someone), as a lover.

Answers.com:
Love is a deep, tender, ineffable feeling of affection and solicitude toward a person, such that arising from kinship, recognition of attractive qualities, or a sense of underlying oneness.
Love is a feeling of intense desire and attraction toward a person with whom one is disposed to make a pair; the emotion of sex and romance.
Love is an intense emotional attachment, as for a pet or treasured object.
Love is a person who is the object of deep or intense affection or attraction; beloved.

To love is to have a deep, tender, ineffable feeling of affection and solicitude toward (a person).
To love is to have a feeling of intense desire and attraction toward (a person).
To love is to have an intense emotional attachment to.

To love is to experience deep affection or intense desire for another.