Ignorance of one thing can lead to errors about other things. I'm an ignorant little twerp when it comes to Latin (though I hope to remedy this twerpishness), and consequently misunderstood the meaning of the word "host" in reference to the Body of Christ in the Eucharist.
It's not "host" in the sense of "I'm Jay Leno, your host tonight." It's not that the Host receives a guest or entertains us.
I'm happy to be able to say that I never made this particular mistake, although I was confused by the use of the word "Host" with reference to the Body.
Rather, it comes from the Latin word hostia - which means victim. At last things make sense. :-) Christ is indeed the sacrificial victim by whose death our sins are forgiven.
This Latin moment brought to you by the English translators of the Summa Theologica, who helpfully included a note explaining this at ST III Q73 A4 obj. 3 (or vol. IV, p. 2430, if you want to see it in the actual book).