What does the term 'admission' refer to in the context of U.S. immigration law?

In the context of U.S. immigration law, the term 'admission' specifically refers to lawful entry into the United States after inspection by an immigration officer. This process is crucial because it signifies that the individual has been evaluated and cleared to enter the country, aligning with the legal frameworks and guidelines established by immigration laws.

During this inspection, individuals must demonstrate that they meet the requirements for entry, such as having the appropriate visa or waiver, and not being subject to any grounds of inadmissibility. This concept is essential in understanding the distinction between individuals who may be present in the U.S. without lawful status and those who have been formally admitted.

The other options do not accurately capture the definition of admission. Exiting the U.S. pertains to departure, while the process of becoming a citizen involves naturalization rather than admission. Returning to the U.S. after being abroad may not involve a new inspection and could occur under various circumstances but does not inherently imply a formal admission as defined by immigration law.