n. & adj.
--n. a flash of bright light produced by an electric discharge between clouds or between clouds and the ground.
--attrib.adj. very quick (with lightning speed).
Phrases and idioms:
lightning-conductor (or -rod) a metal rod or wire fixed to an exposed part of a building or to a mast to divert lightning into the earth or sea. lightning strike a strike by workers at short notice, esp. without official union backing.
Etymology: ME, differentiated from lightening, verbal noun f. LIGHTEN(2)