This lexicon collected by Reinhard.

BTW:By The Way

IM(H)O: In My (Honest) Opinion

Coiler: One of us. A person who plays (works) with Tesla coils.

HFor RF: High Frequency or Radio Frequency.  The operating frequency 
of a Tesla Coil. Usually from 60-700khz

HV: High Voltage

Variac: Variable AC Transformer, allows a gradual increase in voltage.

Former: The secondary coil form.

Toroid: A donut shaped top electrode.  Its capacitance loads the secondary coil, 
drop its resonant frequency and it holds off the breakout. Energy stored in the 
toroid (~capacitor) gives us longer arcs.

Lossy: Material experiencing electrical losses (in the form of heat) at Tesla coil
frequencies. PVC is a lossy material for cap construction (as dielectricum).
Minimize use of lossy material to maximize output.

OBIT: Oil Burner Ignition Transformer

NST: Neon Sign Transformer

PT: Potiential Transformer (a mid sized version of a pig)

PIG or POLE PIG : A power line distribution transformer (also called POLE PIG)

MOT: Microwave Oven Transformer

DWC: Disruptive Wave Coil, a spark gap powered Tesla Coil.

CW(TC): Continuous Wave Tesla Coil: A TOOB or solid state (yuck) TC.

Resonant Charging: A condition where the primary capacitor resonates at 
the mains frequency with the power transformer.  This allows the 
transformer to deliver more voltage than its faceplate rating.

Banjo Effect: A wavy streamer which looks like a swinging banjo string.

Streamer: A spark from the TC not hitting anything, just branching into air.

Arc or Strike or Hit: A streamer connecting to a grounded object.

Strike Rail: A conductor connected to RF ground to intercept hits.
Often an open (!) turn above the primary coil.

Breakout: This is the voltage where a streamer or arc starts to form

Plasma Globe: 
An semi-evacuated glass envelope powered by HF/HV exhibiting tesla like streamers
inside of the glass.

PE: Polyethelene

Rolled Poly Cap: A (usually oil filled) cap made from PE sheets and AL foil 
and then rolled up.

SW Cap: Salt Water Capacitor. Very cheap and easy to build, but very lossy.

Flat Cap: A capacitor made from stacking flat plates on top of each other.

SF(S)G: Saftey Spark Gap

Multi Gap: A series arrangement of spark gaps

SG: Spark Gap (also called Static Gap)

RQ gap: Richard Quick Spark Gap

TF Gap: A modified type of RQ Gap from Terry Fritz (our moderator)

RSG: Rotary (moving electrode) Spark Gap

SRSG: Synchronos Rotary Spark Gap

ASRSG: ASynchronos Rotary Spark Gap

Q: Quality Factor of a resonant circuit, the ratio of its reactive to resistive parts. 
A high Q circuit rings like "diiinnngggg....."  a low Q one rings like "donk"

Quench: Ability of a spark gap to shut off, cease conducting current.

1st or 2nd or 3rd or... notch quenching :  (Terry's posted explanation)

After the gap fires, ringing energy couples from the primary system to the
secondary system.  If the gap continues to conduct, the energy in the
secondary system will return to the primary system, and will continue to 'slosh'
back and forth from primary to secondary until the gap either quenches or the 
system runs down due to losses.  

When the gap quenches after the first energy transfer, it is first notch quenching.  
If it takes two or three complete transfers, it is second or third notch quenching. 
After that, it is usually considered as "no quenching" or "fails to quench".  We 
usually want to quench on the first notch, before energy wasted to system losses.