noun
one-way mirror; two-way mirror
A mirror that is reflective on one side and transparent on the other, used for observation without being seen. Wasei-eigo from English 'magic mirror'.
wasei-eigo (Japanese-coined English), from magic mirror
取調室にはマジックミラーが設置されている。
A one-way mirror is installed in the interrogation room.
あの部屋の窓はマジックミラーになっ
The window of that room is a one-way mirror, so you can't see inside from outside.