a small pocket designed to hold a pocket watch; a watch pocket.
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a small pocket designed to hold a pocket watch, sometimes found in men's trousers and waistcoats and in traditional blue jeans. However, due to the decline in popularity of pocket watches, these pockets are rarely used for their original intended purpose.
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if you mean to ask whether I have something beating just under my fob (excuse the antiquated word, but as I wear the thing in question I must necessarily use the name), why then, most undoubtedly I have.
Grant Allen. Strange Stories.
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He turned suddenly from a chip of strawberries, drew a gold watch from his fob and held it at its chain’s length.
James Joyce. Ulysses
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He was dressed like any other ordinary gentleman, in a loose grey morning coat and waistcoat, and white trousers; and had his watch in his fob, and his money in his pockets: which he rattled as if he were very proud of it.