General term for a liquid that dissolves another substance; used in chemistry, industry, and everyday contexts.
This paint contains an organic solvent.
Use a solvent to remove oil stains.
hot charge
Only when written 溶材
Metallurgical term for a molten material added to a furnace; restricted to the rare kanji form 溶材.
At the steel plant, they charge the furnace with hot charge.
シンナー refers specifically to paint/lacquer thinner, while 溶剤 is the general chemical term for any solvent used to dissolve substances.
organic solvent
Standard kanji spelling for solvent; high frequency in news.
Rare variant used specifically for the 'hot charge' sense in metallurgy.
Rare variant using 熔 (melting) instead of 溶 (dissolving); sometimes seen in older texts.
Compound of 溶 (dissolve) and 剤 (agent, preparation). The variant 熔剤 uses 熔 (melt) and is less common.