Plagiarius, the Latin source of plagiary, literally means "kidnapper." Plagiarius has its roots in the noun plagium, meaning both "kidnapping" and "the netting of game," and ultimately in the noun plaga, meaning "net."
The literal sense of plagiarius was adopted into English; in the 17th and early 18th century, a kidnapper might be referred to as a plagiary, and, in the legalese of the time, kidnapping as plagium.
Plagiarius also referred to a literary thief—and that sense was lifted into the English language in the word plagiary, which can be used for one who commits literary theft (now usually referred to as a plagiarist) or the act or product of such theft (now, more commonly, plagiarism).
Valedictory (val-uh-DIK-tuh-ree) of or relating to an act of bidding farewell: expressing or containing a farewell. Since a valedictory speech is given at the end of an academic career, it is perfectly in keeping with the meaning of its Latin ancestor, valedicere, which means "to say farewell."
When the ancient Greeks had questions or problems, they would turn to the gods for answers by consulting an oracle. The word oracle has several meanings. It can refer to the god's answer, to the shrine that worshippers approached when seeking advice, or to the person through whom the god communicated, usually in the form of cryptic verse. The words oracular and oracle trace back to the Latin verb orare, which means "to speak."
Today, oracle can simply mean an authoritative pronouncement or a person who makes such pronouncements—for example, "a designer who is an oracle of fashion." The related adjective oracular is used in similar contexts: "a designer who is the oracular voice of fashion."
Liberare: Latin, to set free, to liberate