A more thorough explanation:

Definition: Infra aetatem (in-fruh ee-tay-tuhm) is a Latin term that means underage.

Examples:

• John was not allowed to vote because he was still infra aetatem.
• The legal drinking age in the United States is 21, so anyone under that age is considered infra aetatem.

The examples illustrate that infra aetatem refers to someone who is not yet of legal age to do something. In the first example, John is not allowed to vote because he is not yet 18 years old, which is the legal voting age in most countries. In the second example, anyone under 21 is not allowed to purchase or consume alcohol in the United States, making them infra aetatem.