The difference between "madam" and "ma'am". "Ma'am" is a contracted or abbreviated form of "madam" with the apostrophe in "ma'am" representing the omitted "d." "Madam" is often used in more formal or professional settings, while "ma'am" is used in both formal and informal settings. "Madam" is considered traditional, and "ma'am" is 2 Answers. As far as I know, ma'am does not mean mother. It's a contraction of madam. You use ma'am or madam to address a woman politely. It is a sign of deference and it's similar to calling a man "sir". Ma'am and madam are formal, but madam is more formal than ma'am. Ma'am is used more often than madam in recent years. Ampere. Definition: The ampere (symbol: A), often referred to as simply amp, is the base unit of electric current in the International System of Units (SI). The ampere is defined formally based on a fixed value for the elementary charge, e, of 1.602176634 × 10-19 when expressed in the unit C, which is equal to A·s. The second is defined based on the cesium frequency, Δ ν Cs. Dear Madam: it is correct to use "Dear Madam", "Dear Ma'am" or "Respected Madam" as the opening greeting in an email or letter when addressing a woman. Hello: if you want to send an informal or even a formal letter or email to people you know well, it is acceptable to begin it with a casual greeting like "Hello." You can also use "Hi." dhjj7.