shoefly
n.— «Shoefly. Labor spy.» —“Transit” by Jose Casey, Dispatcher, Fifth Ave. Coach Co., 135th St. & Bdwy, N.Y.C.; CIO Transport Workers Union, 153 WEst 64th St., N.Y.C., Coachmen’s Division; Greulich; Rosenberg in New York City Lexicon of Trade Jargon , 1938-39. (source: Double-Tongued Dictionary)
Further reading
If you speak a second or third language, you may remember the first time you dreamed in that new tongue. But does this milestone mean you’re actually fluent? And a couple’s dispute over the word regret: Say you wish you’d been able...