rumble
— Verb
– English
~ to utter or emit low dull rumbling sounds; "he grumbled a rude response"; "Stones grumbled down the cliff"
rumble
— Verb
– English
~ make a low noise; "rumbling thunder"
ruminate
— Verb
– English
~ reflect deeply on a subject; "I mulled over the events of the afternoon"; "philosophers have speculated on the question of God for thousands of years"; "The scientist must stop to observe and start to excogitate"