Stroboscope

noun
1.
a device for studying the motion of a body, especially a body in rapid revolution or vibration, by making the motion appear to slow down or stop, as by periodically illuminating the body or viewing it through widely spaced openings in a revolving disk.
2.
Photography.

Also called strobe, strobe light, stroboscopic lamp. a lamp capable of producing an extremely short, brilliant burst of light, for synchronization with a camera having a high shutter speed, in order to photograph a rapidly moving object, as a bullet, for such a short duration that it will appear to be standing still.
the device and equipment for holding and firing such a lamp.

3.
such a lamp used for creating special lighting effects, as in a theater or discotheque or at a rock concert.
noun
1.
an instrument producing a flashing light, the frequency of which can be synchronized with some multiple of the frequency of rotation, vibration, or operation of an object, etc, making it appear stationary. It is used to determine speeds of rotation or vibration, or to adjust objects or parts Sometimes shortened to strobe
2.
a similar device synchronized with the opening of the shutter of a camera so that a series of still photographs can be taken of a moving object
stroboscope
(strō’bə-skōp’)
Any of various instruments used to observe moving objects by making them appear stationary, especially with pulsed illumination or mechanical devices that intermittently interrupt observation.