How do you define joy?

This is still a work in progress but it seems I was running out of time...
I have been working on this altered book on and off for a year- it's an old book I'm filling with photos I've taken and then I paint/collage them.  This photo was taken on a beautiful day at the New York Botanical Garden.  There was a fabulous Henry Moore sculpture exhibit ( the photo part is half  Moore sculpture, half Marla paint and Maddy imitating art; the grey triangle is also a Henry Moore sculpture) throughout the gardens.  I went with my sister and mother and our girls.  The only word I can think of that truly describes the day we spent there is joy.