( n. )
An opera glass or field glass with an oblique mirror arranged for seeing objects do not lie directly before the eye; -- called also diagonal, / side, opera glass.
( n. )
An opera glass or field glass with an oblique mirror arranged for seeing objects do not lie directly before the eye; -- called also diagonal, / side, opera glass.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012