extend and lengthen imply a drawing out in space or time but extend may also imply increase in width, scope, area, or range.
extend a vacation
extend welfare services
lengthen a skirt
lengthen the workweek
prolong suggests chiefly increase in duration especially beyond usual limits.
prolonged illness
protract adds to prolong implications of needlessness, vexation, or indefiniteness.
protracted litigation
Examples of prolong in a Sentence
Additives are used to prolong the shelf life of packaged food.
High interest rates were prolonging the recession.
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Resources spent to prolong one person’s final years are resources not spent elsewhere, including on younger generations or other public health measures.—James Broughel, Forbes.com, 27 Jan. 2026 Tens of millions of Americans were under alerts for severe cold as a blast of Arctic air prolonged below-freezing temperatures, according to the National Weather Service.—Thao Nguyen, USA Today, 27 Jan. 2026 If the power is going to be out for longer than a day, put some food into coolers with ice to prolong their safe consumption.—Hannah Hudnall, IndyStar, 23 Jan. 2026 The drug also causes food to linger in the stomach, which prolongs the feeling of fullness.—Christina Stiehl, SELF, 23 Jan. 2026 See All Example Sentences for prolong
Word History
Etymology
Middle English, from Middle French prolonguer, from Late Latin prolongare, from Latin pro- forward + longus long