Answer:
noun
1.
a length or portion of time.
"he had long periods of depression"
2.
PHYSICS
the interval of time between successive occurrences of the same state in an oscillatory or cyclic phenomenon, such as a mechanical vibration, an alternating current, a variable star, or an electromagnetic wave.
ʜᴏᴘᴇ ᴘᴏ ɴᴀᴋᴀ ᴛᴜʟᴏɴɢシ︎
