flunk

verb

1. 1

   Of a student, to fail a class; to not pass.

   “He flunked math, again.”

2. 2

   Of a teacher, to deny a student a passing grade.

   “Unsatisfied with Fred's progress, the teacher flunked him.”

3. 3

   To shirk (a task or duty).

4. 4

   To back out through fear. (Commonly in the phrase 'flunk it', the 'it' referring to a specific task avoided; sometimes without specific reference describing a person's attitude to life in general.)