for·mu·la / ˈfôrmyələ/ • n. 1. (pl. -las or -lae / -ˌlē; -ˌlī/ ) a mathematical relationship or rule expressed in symbols. ∎  (also chemical formula) a set of chemical symbols showing the elements present in a compound and their relative proportions, and in some cases the structure of the compound. See empirical formula, molecular formula, structural formula.2. (pl. -las) a fixed form of words, esp. one used in particular contexts or as a conventional usage: a legal formula. ∎  a method, statement, or procedure for achieving something, esp. reconciling different aims or positions: the forlorn hope of finding a peace formula. ∎  a rule or style unintelligently or slavishly followed: [as adj.] one of those formula tunes. ∎  a statement that formally enunciates a religious doctrine. ∎  a stock epithet, phrase, or line repeated for various effects in literary composition, esp. epic poetry.3. (pl. -las) a list of ingredients for or constituents of something: the soft drink company closely guards its secret formula. ∎  a formulation: an original coal tar formula that helps prevent dandruff. ∎  an infant's liquid food preparation based on cow's milk or soy protein, given as a substitute for breast milk.4. (usually followed by a number) a classification of race car, esp. by engine capacity.

formula set form of words XVII; recipe; rule, etc., expressed by symbols XVIII. — L. fōrmula, dim. of fōrma FORM see -ULE.
So formulary collection or system of formulas. XVI. formulate XIX.

formula (form-yoo-lă) n.
1. a representation of the structure of a chemical compound using symbols and subscript numbers for the atoms it contains (e.g. H₂O for water; CO₂ for carbon dioxide).

2. a prescription for a drug.