means Either a verb expressing possibility or permission (it might rain; you might leave now) or a noun meaning great strength or power (with all his might).

from Two ancient threads twisted into one spelling. The strength-noun "might" comes from Old English miht, rooted in the Germanic verb of being able — the same family that gave us "may" and "main." The cautious verb "might" is simply the old past tense of "may" (Old English meahte/mihte), which once meant "was able to." So the loaded coin isn't really two words but one deep root for capability, where raw power and tentative possibility were always cousins: to be able to do something, and to be strong enough to do it.