taru-adjective, adverb taking the 'to' particle
Formal or literary term describing liquid falling drop by drop. Often used adverbially with と.
Rain was dripping down along the eaves.
The sound of trickling water echoed in the quiet room.
Reduplication of 滴 (てき, 'drop'), forming a literary adjectival/adverbial expression meaning 'dripping' or 'trickling'.