1. The movement used to launch a paper football, or to punish someone who has just said something mildly obnoxious, in which case it is generally directed at the forehead. You simply place the tip of a finger against the pad of your thumb and then snap the finger forward. Also the act of filliping or the position your fingers are in prior to executing a fillip.
2. Something of minor importance.
3. A short period of time; a moment.
4. A sharp blow, or the act of delivering such a blow.
5. A stimulus; something that excites, enlivens, interests, etc. Also, to stimulate or urge, often with "forward."
This charming quote from Thomas Becon's "An Invective Against Swearing" illustrates several of these meanings:
"The blasphemy done to a mortal man is punished with the sword, and shall the blasphemy done to God escape think you with a fillip in the forehead, or with the knock of a little wooden betel, as it is begun to be punished in certain men's houses now of late? Nay, verily. It is no fillip matter except we will admit such a fillip as shall fillip them down into the bottom of hell-fire." [Emphasis mine.]
I thought this was a cute word. Now it kind of scares me.