A more thorough explanation:

M. can mean different things depending on the context:

1. MORTGAGE: M. is an abbreviation for the word "mortgage." A mortgage is a loan that you take out to buy a property, like a house or a piece of land. You pay back the loan over time, usually with interest.
2. Historical: In the past, M. was used in different ways:
• A letter engraved on a treasury note to show that the note bears interest at the rate of one mill per centum.
• A brand placed on the left thumb of a person convicted of manslaughter who claimed the benefit of clergy.

Here are some examples to help you understand how M. can be used:

• MORTGAGE: John took out a $200,000 M. to buy his dream home.
• Historical: In the 19th century, some treasury notes had the letter M. engraved on them to indicate that they earned a very small amount of interest.
• Historical: In medieval times, if someone committed manslaughter but could read, they could claim the benefit of clergy and avoid the death penalty. However, they would be branded with the letter M. on their thumb as a sign of their crime.

These examples show that M. can have different meanings depending on the context. In the first example, M. stands for "mortgage," which is a type of loan. In the second and third examples, M. is a historical abbreviation that was used to indicate interest on treasury notes or to brand convicted criminals.