Why is the ninth month called September?
1630s, "words used in a ceremony or ritual," from Latin formula "form, draft, contract, regulation; rule, method, formula," literally "small form," diminutive of forma "form" (see form (n.)).
Modern sense is colored by Carlyle's use (1837) of the word for "rule slavishly followed without understanding" [OED].
Men who try to speak what they believe, are naked men fighting men quilted sevenfold in formulae. [Charles Kingsley, "Letters," 1861]Mathematical use is from 1796; use in chemistry is from c.1846.
formula for·mu·la (fôr'myə-lə)
n. pl. for·mu·las or for·mu·lae (-lē')
A symbolic representation of the chemical composition or of the chemical composition and structure of a compound.
The chemical compound so represented.
A prescription of ingredients in fixed proportion; a recipe.
A liquid food for infants, containing most of the nutrients in human milk.
A mathematical statement, especially an equation, of a fact, rule, principle, or other logical relation.
Plural formulas or formulae (fôr'myə-lē')