Gound

   When I was a child, if one rubbed one’s eyes upon waking up the natural question to be asked was ‘Have you got sleep in your eyes?”  ‘Sleep’ in that context was a colloquial word for gound, the matter that collects in the corner of the eyes or on the eyelashes when rheum dries.  Although gound and rheum are sometimes said to be synonymous they aren’t. Gound is solid matter whilst rheum is thin mucus naturally discharged as a watery substance from the eyes, nose, or mouth; the word rheum coming from the Greek for ‘to flow’.

All this probably comes under the heading ‘Things one didn’t wish to know!’