1. [n]  a sound with a strong rhythmic beat; "the throbbing of the engines"
2. [n]  an instance of rapid strong pulsation (of the heart); "he felt a throbbing in his head"
3. [adj]  pounding or beating strongly or violently; "a throbbing pain"; "the throbbing engine of the boat"

THROBBING is a 9 letter word that starts with T.