Gen. Douglas MacArthur’s surgeon, Col. Roger O. Egeberg, stepped on a semantic land mine when he casually referred to MacArthur’s troops as G.I.s. The general immediately exploded: “Don’t ever do that in my presence… . G.I. means ‘general issue.’ Call them soldiers.” It seems safe to assume that Colonel Egeberg never made that mistake again.

Today, of course, most people use G.I. approvingly when referring to enlisted personnel. (But beware of calling a Marine a G.I.!) The abbreviation crops up all over the place, particularly in headlines and captions, where writers look for ways to cram news into tight spaces, as in, from The New York Times , G.I.S TO PULL BACK IN BAGHDAD (Feb. 2, 2004) and G.I.S TO INCREASE U.S. SUPERVISION OF IRAQI POLICE (Dec. 20, 2005).

Also testifying to G.I. ’s staying power over the years is its appearance in a great many combinations. Among them: G.I. Joe , an enlisted man; G.I. Jane , a member of the Women’s Army Corps (WAC) in World War II, but nowadays any female soldier, as in a Christian Science Monitor headline, COMBAT FOR G.I. JANES IN IRAQ (Jan. 27, 2005); G.I. bride , a foreign woman married to an American soldier; G.I. gin , cough syrup; and G.I. Jesus , a military chaplain (of the Christian persuasion).

While General MacArthur took G.I. to mean general issue , the term also has been interpreted over the years as standing for garrison issue , government issue , general infantry , and galvanized iron . And as it happens, the last, which might seem to be the least likely, is the true progenitor. In brief, this is the sequence:

G.I. appears in Army inventories of galvanized-iron trash cans and buckets from the early twentieth century. The oldest known example, “Bucket, G.I. on strap near axle under body,” refers to cavalry maneuvers near Fort Riley, Kansas, in 1906 (in A Dictionary of Soldier Talk , by Col. John Elting et al., 1984).

During World War I the meaning of G.I. can was extended to include heavy German artillery shells and large bombs, while G.I. itself began to be applied in the MacArthurian sense of “general issue” to such items as G.I. shoes , G.I. soap , and G.I. brushes . Soldiers probably began referring to themselves as G.I.s during this war or shortly thereafter, but no examples have been found in writing prior to 1935, when the abbreviation was recorded as slang for an enlisted man.

The transition from trash cans to soldiers may have been aided by the roughness and toughness of galvanized iron. According to an anonymous sergeant, who had served in the Army for many years, the term originally was considered insulting because “a man who was G.I. was crude or uncouth” (