n.

1. （应酬话等的）惯用语句，客套话[C]
   "How do you do?" is a polite formula.

   “您好。”是客气的套语。

2. 惯例，常规；准则，方案[C][（+for）]
   A formula for settling the border dispute has been worked out.

   已拟定一个解决边界纠纷的方案。

3. 配方，处方[C][（+for）]
   The formula of the medicine is still a secret.

   此药的配方仍是秘密。

4. 【数】公式；方程式[C][（+for）]
5. 【化】分子式[C][（+for）]
6. 【美】配制成的婴儿奶粉或奶水[U]
   If you are not planning on breastfeeding, you have to decide on a formula.

   如果你不打算喂母奶，那么你得决定选一种婴儿奶粉（水）。

n.

1. (pl. formulae /-liː/ )
   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.
2. (pl. formulas)
   a method or procedure for achieving something.
   ▸a list of ingredients with which something is made.
   ▸ (also formula milk) a baby's liquid food based on cow's milk or soya protein.
3. (pl. formulas)
   a fixed form of words, especially one used in particular contexts or as a conventional usage.
   ▸a rule or style mechanically followed.
4. (usually followed by a numeral) a classification of racing car, especially by the engine capacity.