fillip

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A snap or light blow made by pressing a fingertip against the thumb and suddenly releasing it.
2. n. An embellishment that excites or stimulates: "Spritely tabasco onions, just a little crunch for the top, were an added fillip” ( Alison Arnett).
3. n. One that is trivial or of little importance.
4. v. To strike or propel rapidly by as or as if by a fillip: filliped his finger against my ear; filliped the pretzel across the counter.
5. v. To stimulate or arouse.

Century Dictionary and Cyclopedia

1. To strike slightly or with some light instrument; especially, to strike with the nail of a finger first bent against the ball of the thumb, and let fly from that position with some force.
2. To strike, nudge, or touch, as a horse or a person, in order to urge or press forward; incite; drive.
3. To strike or tap with the nail of the finger.
4. n. A jerk of a finger bent against the ball of the thumb, and then suddenly let fly; hence, a smart tap or stroke.
5. n. Anything which tends to rouse, excite, or revive: as, that acted as a fillip to my spirits.

Wiktionary

1. n. A flick; the act of releasing the index finger from the hold of a thumb with a snap.
2. n. Something that excites or stimulates.

GNU Webster's 1913

1. v. To strike with the nail of the finger, first placed against the ball of the thumb, and forced from that position with a sudden spring; to snap with the finger.
2. v. To snap; to project quickly.
3. n. A jerk of the finger forced suddenly from the thumb; a smart blow.
4. n. Something serving to rouse or excite.

WordNet 3.0

1. n. anything that tends to arouse