counter for cupfuls, bowlfuls, spoonfuls, etc.
Archaic reading of 杯 used as a counter for containers. In modern Japanese, 杯 is read はい for this meaning. This reading may appear in historical texts or classical contexts.
See also: 杯 (はい)
In classical texts, it was used like 'one cup of sake'.
Archaic reading of 杯; the historical derivation is uncertain.