'Tribulation' in the Bible

yet hath he not root in himself, but endureth for a while; and when tribulation or persecution ariseth because of the word, straightway he stumbleth.

Then shall they deliver you up unto tribulation, and shall kill you: and ye shall be hated of all the nations for my name's sake.

for then shall be great tribulation, such as hath not been from the beginning of the world until now, no, nor ever shall be.

But immediately after the tribulation of those days the sun shall be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken: