He had not dared to return to the Room of Requirement to retrieve his book, and his performance in Potions was suffer-ing accordingly (though Slughorn, who approved of Ginny, had jocularly attributed this to Harry being lovesick).
There are no more uses of "jocular" in the book.
Show samples from other sources
"Oops!" her father agreed jocularly.
Sara Shepard -- Pretty Little Liars
"You’re rude, jocular; and the one time you do something serious, it tears at the fabric of our nation.