Pitter-Patter is a 13 letter English word.
You can make 303 anagrams from letters in pitter-patter (-aeeipprrtttt).
1400-50; late Middle English: a babbled prayer; perhaps imitative
Then came the pitter-patter of claws upon the smooth surface of the ice.
Up and down the children ran, with a pitter-patter of clamouring feet on the leads.
She had not gone far when she heard the pitter-patter of feet.
There was stillness; no battery, however distant, no pitter-patter of rifle fire, no chattering report of the machine guns.
My heart kept up its pitter-patter as I continued reading down the thread.
At length there was a pitter-patter, pitter-patter, and some bits of mortar fell from the wall above.
The others followed, pitter-patter down the stairs, and along the gravelled path.
Jack a little later heard the cat-like steps of its mate leaving the place, until the pitter-patter died away in the distance.
The noise kept on, "pitter-patter; pitter-patter-patter-pitter; pat-pit-pat-pit."