I don't know if I have a single favourite word, but since I first heard it, I've loved the word 'chiaroscuro', which means the contrast of light and shadow (especially in art). Wikipedia uses the example of the attached painting to illustrate it. (Divine Love Conquering Earthly Love by Giovanni Baglione)
I thought you might enjoy this article, full of wonderful made-up words (and some beautiful artwork):
I love this one:
SUERZA
n. a feeling of quiet amazement that you exist at all; a sense of gratitude that you were even born in the first place, that you somehow emerged alive and breathing despite all odds, having won an unbroken streak of reproductive lotteries that stretches all the way back to the beginning of life itself.
Spanish suerte, luck + fuerza, force. Pronounced “soo-wair-zuh."