أرجو شرح كلمتي البرق والسحاب؟

"Barq" (lightning) originates from "bareeq" (gleam/shine) and "dhaw' " (light). One says, "The sky thundered with thunder (ra'd) and flashed with lightning (barq)." As for "sahab" (clouds), its singular is "sahabah," which means a cloud. Clouds are called "sahab" because of their trailing/drifting (insihab) in the air.