retumbante
resounding
re-
again, intensifier
+
tumbar
to knock down, to fall
+
-ante
adjective suffix (present participle)
Retumbante means resounding and can be thought of as something that repeatedly0 (re-0) knocks down1 (tumbar1) in an ongoing manner2 (-ante2), like a powerful echo.
adjective
- resoundingResounding or reverberating loudlyEl trueno retumbante sacudió las ventanas de la casa. // The resounding thunder shook the windows of the house.