frus ‧ trat ‧ ing /frʌˈstreɪtɪŋ $ ˈfrʌstreɪtɪŋ/ BrE AmE adjective
making you feel annoyed, upset, or impatient because you cannot do what you want to do:
My job can be very frustrating sometimes.
This is an immensely frustrating experience for the student.