수험생이 · 수험생을
exam taker, test candidate (esp. for the college entrance exam)
Example
수능 날 아침에 수험생들이 시험장으로 들어가고 있어요.
On the morning of the CSAT, test takers are heading into the exam halls.
Word parts
수 receive+험 test+생 student
Literally 'student receiving a test'.
Good to know
Usually means high school seniors preparing for the 수능, though it works for any big exam.