the word 'unfurl' presents a clear example of english building a verb by adding a native prefix to a borrowed verb. the core 'furl' entered english in the late 16th century from the nautical french term ferler, meaning to roll up a sail tightly. the old english prefix 'un-', one of the language's most productive for indicating reversal, was then attached to it. thus, the literal morpheme logic is "to reverse the action of rolling up." from this specific nautical origin, the word's meaning broadened elegantly to describe the opening or spreading out of any rolled or folded object, such as a flag, a banner, or even abstract things like plans.

Structure: un (reverse action) + furl (roll or wrap) un- (old english, prefix meaning "to reverse an action"); furl (middle english, from old french ferler, meaning "to roll up or wrap")