esfumar
fade
fume
smoke or vapor
+
-ar
verb suffix
Esfumar means to fade and can be thought of as fume0 + -ar1, like smoke or vapor0 that fades away.
verb
  1. fade
    To fade away or disappear gradually
    Las nubes se esfumaron lentamente en el cielo. // The clouds slowly faded away in the sky.