"to figure out, investigate and discover," 1966, earlier "to suspect" (1953, police jargon), a slang shortening of suspect (v.). Related: Sussed.
1961, said to be an abbreviation of all (systems) OK; popularized in the jargon of U.S. astronauts. See OK.
1794, circon, also jargon, new name given in chemistry to jacinth, from German Zirkon (Klaproth, 1789), which probably is from 18c. French jargon, a vague mineral word used of high-quality diamond-like gemstones; it has been traced to Medieval Latin jargonce, which is of uncertain origin. Compare Italian giargone, from the same source.
1942, American English slang, the first element probably a nonsense reduplication of suit (compare reet pleat, drape shape from the same jargon).