I've been rereading my Mexican Day of the Dead book recently. I had originally used it for reference when painting 'Ofrenda' (you can see the picture on the PRINTS FOR SALE in my website)
I had made the painting to celebrate the life of my mother and always imagined the word ofrenda meant altar. However I was wrong. It means offering. It seems obvious really as in Mexican culture the relatives celebrate their loved ones by laying out special foods and objects on a kind of altar.
I'm not about to change the title though as my picture used the Mexican tradition as only one of its influences and I think the two words are interchangeable anyway.