SPARK PLUG n.
In internal-combustion engines with electric ignition, a plug, screwed into the cylinder head, having through it an insulated wire which is connected with the induction coil or magneto circuit on the outside, and forms, with another terminal on the base of the plug, a spark gap inside the cylinder.
SPONTANEOUS a. 2 definitions
Proceding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proportion.
TAP n. 2 definitions
A tool for forming an internal screw, as in a nut, consisting of a hardened steel male screw grooved longitudinally so as to have cutting edges. On tap. (a) Ready to be drawn; as, ale on tap. (b) Broached, or furnished with a tap; as, a barrel on tap. -- Plug tap (Mech.), a screw-cutting tap with a slightly tapering e…