Is it ensure, insure, or assure?
Old English sape "soap, salve" (originally a reddish hair dye used by Germanic warriors to give a frightening appearance), from Proto-Germanic *saipon "dripping thing, resin" (cf. Middle Low German sepe, West Frisian sjippe, Dutch zeep, Old High German seiffa, German seife "soap," Old High German seifar "foam," Old English sipian "to drip"), from PIE *soi-bon-, from root *seib- "to pour out, drip, trickle" (cf. Latin sebum "tallow, suet, grease").
Romans and Greeks used oil to clean skin; the Romance language words for "soap" (cf. Italian sapone, French savon, Spanish jabon) are from Late Latin sapo "pomade for coloring the hair" (first mentioned in Pliny), which is a Germanic loan-word, as is Finnish saippua. The meaning "flattery" is recorded from 1853.
1580s, from soap (n.). Related: Soaped; soaping.
A cleansing agent made from a mixture of the sodium salts of various fatty acids of natural oils and fats.
A metallic salt of a fatty acid, as of aluminum or iron.
A substance used for washing or cleaning, consisting of a mixture of sodium or potassium salts of naturally occurring fatty acids. Like detergents, soaps work by surrounding particles of grease or dirt with their molecules, thereby allowing them to be carried away. Unlike detergents, soaps react with the minerals common in most water, forming an insoluble film that remains on fabrics. For this reason soap is not as efficient a cleaner as most detergents. The film is also what causes rings to form in bathtubs. Compare detergent.
(Jer. 2:22; Mal. 3:2; Heb. borith), properly a vegetable alkali, obtained from the ashes of certain plants, particularly the salsola kali (saltwort), which abounds on the shores of the Dead Sea and of the Mediterranean. It does not appear that the Hebrews were acquainted with what is now called "soap," which is a compound of alkaline carbonates with oleaginous matter. The word "purely" in Isa. 1:25 (R.V., "throughly;" marg., "as with lye") is lit. "as with _bor_." This word means "clearness," and hence also that which makes clear, or pure, alkali. "The ancients made use of alkali mingled with oil, instead of soap (Job 9:30), and also in smelting metals, to make them melt and flow more readily and purely" (Gesenius).