hijacking

The term 'hijack' emerged in American English during the Prohibition era of the 1920s, initially referring to the robbery of illegal liquor shipments. Its exact origin is obscure but is popularly thought to be a criminal slang compound, possibly from the command "High, Jack!" or "Hi, Jack!" used by robbers. The '-ing' suffix is a common Germanic-derived nominalizer forming action nouns from verbs. From its specific criminal beginnings, the meaning broadened dramatically in the mid-20th century to its most prominent modern sense—the unlawful seizure of an aircraft—and later extended metaphorically to the unauthorized takeover of any process or system, such as a meeting or a computer session.

The word 'hijacking' is a modern English derivative formed from the verb 'hijack' (itself of uncertain, likely 20th-century American origin) + the nominal suffix '-ing'. The verb 'hijack' is considered a simplex unit; its components 'hi' and 'jack' are not productive morphemes in this context and do not contribute independent meaning.