1. Of a motor or engine, to emit a series of irregular, erratic popping or spitting sounds before shutting off. I got the lawnmower running, but it sputtered out before too long. The car started sputtering out while we were in the middle of the highway.

2. Of a flame, to be extinguished after emitting a few final puffs of fire. The candles all sputtered out as the breeze blew through the house. The campfire sputtered out as the rain intensified.

3. Of an action, intention, plan, etc., to gradually decrease or weaken in intensity, enthusiasm, or activity before failing or ceasing altogether. It seems like their plans to get into smartphone app development is beginning to sputter out. No, I don't have a back-up plan—I didn't expect this idea to sputter out so fast. Unfortunately, consumers' enthusiasm for our project sputtered out after we ran into so many delays.