noun
Etymology: so called from its opening like the wings of a butterfly
: a movable steel dam pivoted at top and bottom and opened and closed by a rack-and-pinion mechanism and electric motor
noun
Etymology: so called from its opening like the wings of a butterfly
: a movable steel dam pivoted at top and bottom and opened and closed by a rack-and-pinion mechanism and electric motor
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012