I have to add something to the word of the day, because I feel that there is something missing in the explanation given by AWAD - at least for English speakers.
The first meaning of "spogliare" coming in my mind is "to undress" - from this meaning the others meanings come in this way : after a battle, the winners take all the clothes - and, by extension, all the valuable things - of the losers, leaving them naked and without anything...from this idea, the meaning of plundering.