by 1910, American English underworld slang, from hobo slang, "naive young boy," but especially "a catamite;" specifically "a young male kept as a sexual companion, especially by an older tramp," from Yiddish genzel, from German Gänslein "gosling, young goose" (see goose (n.)). The secondary, non-sexual meaning "young hoodlum" seems to be entirely traceable to Dashiell Hammett, who sneaked it into "The Maltese Falcon" (1929) while warring with his editor over the book's racy language:
"Another thing," Spade repeated, glaring at the boy: "Keep that gunsel away from me while you're making up your mind. I'll kill him."
The context implies some connection with gun and a sense of "gunman," and evidently that is what the editor believed it to mean. The word was retained in the script of the 1941 movie made from the book, so evidently the Motion Picture Production Code censors didn't know it either.
The relationship between Kasper Gutman (Sidney Greenstreet) and his young hit-man companion, Wilmer Cook (Elisha Cook, Jr.), is made fairly clear in the movie, but the overt mention of sexual perversion would have been deleted if the censors hadn't made the same mistaken assumption as Hammett's editor. [Hugh Rawson, "Wicked Words," 1989, p.184]
mid-14c., sedicioun, "rebellion, uprising, revolt, factitious commotion in the state; concerted attempt to overthrow civil authority; violent strife between factions, civil or religious disorder, riot; rebelliousness against authority," from Old French sedicion (14c., Modern French sédition) and directly from Latin seditionem (nominative seditio) "civil disorder, dissension, strife; rebellion, mutiny," literally "a going apart, separation." This is from sed- "without, apart, aside" (see se-) + itio "a going," from ire "to go" (from PIE root *ei- "to go").
In early use, 'factious with tumult, turbulent' (J.); now chiefly, engaged in promoting disaffection or inciting to revolt against constituted authority [OED]
The meaning "conduct or language inciting to rebellion against a lawful government" is attested by 1838. Less serious than treason, as wanting an overt act.
But it is not essential to the offense of sedition that it threaten the very existence of the state or its authority in its entire extent. Thus, there are seditious assemblies, seditious libels, etc., as well as direct and indirect threats and acts amounting to sedition — all of which are punishable as misdemeanors by fine and imprisonment. [Century Dictionary]
Latin seditio was glossed in Old English by unsib, folcslite.