Rainbow

Boyd’s Bible Dictionary:

A sign of the covenant that the earth should not again be destroyed by water

Concise Bible Dictionary:

The “bow set in the clouds” was given by God to Noah as a token that He would not again destroy the world by a flood (Gen. 9:13-1613I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. 14And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud: 15And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh. 16And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth. (Genesis 9:13‑16)). That the rainbow, as is now known, is caused by the refraction of light on drops of rain, need not cause any difficulty. The rainbow may have appeared to Noah before, but it was not appointed by God as a token until after the flood. The word translated “set” (nathan) is sometimes translated “appoint,” as in Joshua 20:22Speak to the children of Israel, saying, Appoint out for you cities of refuge, whereof I spake unto you by the hand of Moses: (Joshua 20:2). Others judge it to be more probable that the rainbow had not been seen prior to the flood, the state of the atmosphere being different from what it became after the deluge.

Strong’s Dictionary of Greek Words:

Number:
2463 (find all occurrences in KJV Bible)
Greek:
ἶρις
Transliteration:
iris
Phonic:
ee’-ris
Meaning:
perhaps from 2046 (as a symbol of the female messenger of the pagan deities); a rainbow ("iris")
KJV Usage:
rainbow