pitter-patter(n = noun.event) - a series of rapid tapping sounds; "she missed the pitter-patter of little feet around the house"
is a kind of pat, rap, tap
Derived form verb pitter-patter₂

1.  pitter-patter(v = verb.weather) patter, spatter, spit, sprinkle - rain gently; "It has only sprinkled, but the roads are slick"
is one way to rain, rain down
Sample sentences: It is ----ing

2.  pitter-patter(v = verb.perception) patter - make light, rapid and repeated sounds; "gently pattering rain"
is one way to go, sound
Derived form noun pitter-patter₁
Sample sentences: Something ----s; Somebody ----s PP

1.  pitter-patter(r = adv.all) pit-a-pat, pitty-pat, pitty-patty - as of footsteps; "he came running pit-a-pat down the hall"

2.  pitter-patter(r = adv.all) pit-a-pat, pitty-pat, pitty-patty - describing a rhythmic beating; "his heart went pit-a-pat"

   A sound like that of alternating light beats. Also, a pattering of words. [Webster 1913 Suppl.]

   With, or with the sound of, alternating light beats; as, his heart went pitter-patter. [Webster 1913 Suppl.]

pitter-patter, var. of PIT-A-PAT.