A Plain-English Vaping Glossary

Vaping has generated a dense vocabulary of its own, much of it borrowed from electronics and hobbyist culture. This glossary defines the terms you are most likely to meet, in plain language. It is a reference to help you read and understand — nothing here is a recommendation to use any product.

Independent educational resource. Vapor Hub is an information-only reference. Nothing here is for sale, and nothing here encourages anyone to start using nicotine. Intended for adults of legal age (18+ in the UK and EU, 21+ in the United States). This is not medical advice — speak with a qualified professional about your own health. If you do not smoke or vape, the best choice is not to start.

Devices and parts

• Atomiser — the part of a device that heats e-liquid into aerosol; contains the coil and wick.
• Coil — the resistance-wire heating element that vaporises liquid held in the wick.
• Wick — the absorbent material, usually organic cotton, that draws liquid to the coil.
• Mod — the body of a larger device housing the battery and (in regulated mods) the control electronics. Short for “modified.”
• Regulated mod — a device with a circuit board that controls power and provides safety cut-offs.
• Mechanical mod — an unregulated device with no circuit or safety features; advanced use only.
• Pod system — a compact device using small refillable or pre-filled pods that hold liquid and coil together.
• Tank — a sealed reservoir that feeds liquid to a replaceable coil head.
• RDA / RTA / RDTA — Rebuildable Dripping / Tank / Dripping-Tank Atomisers: hobbyist parts on which the user builds their own coils.
• Disposable — a sealed single-use device discarded when empty.

E-liquid terms

• E-liquid / e-juice — the fluid that is vaporised; made of PG, VG, flavourings and optional nicotine.
• PG — propylene glycol, a thin base fluid that carries flavour and gives a firmer throat hit.
• VG — vegetable glycerine, a thicker, slightly sweet base fluid that produces more visible aerosol.
• PG/VG ratio — the proportion of the two bases, e.g. “70/30” meaning 70% VG to 30% PG.
• Nicotine strength — the nicotine concentration, given in mg/ml or as a percentage; capped at 20 mg/ml in the EU and UK.
• Freebase nicotine — traditional nicotine form; can feel harsh at higher strengths.
• Nicotine salts (nic salts) — a smoother, quickly-absorbed nicotine form common in low-power pods.
• Diacetyl — a buttery flavour chemical banned in EU/UK vaping products over inhalation-safety concerns.
• Dry hit — the harsh, burnt taste when the wick runs low on liquid; a signal to refill.

Power and safety terms

• Ohm (Ω) — the unit of electrical resistance; a coil’s resistance sets how much power it draws.
• Sub-ohm — a coil with resistance below one ohm, producing more heat and aerosol; higher power draw.
• Wattage — the power delivered to the coil, adjustable on regulated devices.
• 18650 / 21700 — common sizes of removable cylindrical lithium-ion battery cells.
• mAh — milliamp-hours, a measure of battery capacity (roughly, how long it lasts per charge).
• Continuous discharge rating (CDR) — the maximum current a cell can safely deliver continuously; central to safe use of unregulated devices.
• Thermal runaway — a self-sustaining overheating reaction in a failing lithium cell; the main battery hazard.
• Battery wrap — the thin insulating sleeve on a cell; damage to it is a short-circuit risk.

Practice and policy terms

• Aerosol — the correct term for what is inhaled and exhaled; not “water vapour.”
• Throat hit — the sensation at the back of the throat, influenced by PG ratio and nicotine strength.
• Harm reduction — the public-health approach of reducing the damage of a behaviour for those who continue it.
• TPD — the EU/UK Tobacco Products Directive that sets vaping product limits.
• PMTA — the US FDA Premarket Tobacco Product Application required before a product can be sold.
• EVALI — the 2019 lung-injury outbreak linked to vitamin E acetate in illicit THC products, not regulated nicotine liquids.

For fuller explanations of any of these, follow the relevant page: how vaping works, devices, e-liquid, battery safety or regulation.