I woke up at 4 o'clock this morning with the answer to something that has been puzzling me for the past eighteen months.
In my wind-bands/orchestras, the conductors often ask to start "one before bar 25 (or whatever number)." Sometimes this means one whole bar before, and sometimes one beat before. Everyone else always seems to know exactly where they are supposed to start but, unless the oboe part has the tune (or something really obvious), I seem to get it wrong more often than I get it right.
At 4 o'clock I suddenly realised that "mesure" (bar) is feminine and temps (beat) is masculine so the French speakers hear either "une" (and know it is "une mesure") or "un" (and know it is "un temps") and my brain was translating both as "one."
I don't know what I was dreaming about that made me finally realise this

And then I was so pleased about my "discovery" I couldn't get back to sleep again.