agradecimiento
gratitude
agradecer
to thank
+
-miento
noun suffix (action or state)
Agradecimiento means gratitude and can be thought of as the noun form1 (-miento1) of agradecer0 (to thank0).
noun
- gratitudeThe feeling or expression of being thankfulExpresó su agradecimiento por la ayuda recibida. // He expressed his gratitude for the help received.