Which is the term for the effect in in painting of softer or smokey edges?

The term for the effect of softer or smokey edges in painting is "sfumato." Originating from the Italian Word meaning "to evaporate like smoke," sfumato involves the gradual blending of colors and tones, creating a more atmospheric and subtle transition between different areas of a painting. This technique is famously associated with artists like Leonardo da vinci, who used it to enhance depth and realism in his portraits.