18-letter words containing um
- sodium thiosulfate — a white, crystalline, water-soluble powder, Na 2 S 2 O 3 ⋅5H 2 O, used as a bleach and in photography as a fixing agent.
- sodium-vapour lamp — a type of electric lamp consisting of a glass tube containing neon and sodium vapour at low pressure through which an electric current is passed to give an orange light. They are used in street lighting
- squirting cucumber — a Mediterranean plant, Ecballium elaterium, of the gourd family, whose ripened fruit forcibly ejects the seeds and juice.
- strangeness number — a quantum number, designating the strangeness of an elementary particle, equivalent to the hypercharge minus the baryon number
- strontium monoxide — a white insoluble solid substance used in making strontium salts and purifying sugar. Formula: SrO
- summary proceeding — a mode of trial authorized by statute to be held before a judge without the usual full hearing.
- temporal summation — the act or process of summing.
- the uncircumcision — the gentiles
- thermoluminescence — phosphorescence produced by the heating of a substance.
- third man argument — (in the philosophy of Aristotle) the argument against the existence of Platonic Forms that since the Form of Man is itself a perfect man, a further form (the "third" man) would be required to explain this, and so ad infinitum
- transfinite number — an infinite cardinal or ordinal number.
- transit instrument — Astronomy. meridian circle.
- vanadium pentoxide — a yellow to red crystalline compound, V 2 O 5 , slightly soluble in water, used as a catalyst for organic reactions, in glass to absorb ultraviolet radiation, and as a photographic developer.
- white trumpet lily — a lily, Lilium longiflorum, of Japan, having fragrant, pure white, trumpet-shaped flowers nearly 7 inches (18 cm) in length.