The department responsible for providing information about the school to prospective students, reviewing applications for acceptance to the university, and determining a student's eligibility for admission.
The 8-10 week process that takes place once you've submitted your online application. The admissions department will notify you if your application has been accepted. Submitting your application between October 1 and November 30, meeting the proper requirements and submitting transcripts and other required documents in a timely manner will help to speed the process along.
A school that accepts a student into one of their programs is said to "admit" the student into the school. The admissions department/office of a school manages that process; the receiving and reviewing of new student applications.