A pack or pannier used to carry goods on the back of a pack animal like a horse or donkey.
Possibly from French 'croc' (hook) combined with 'jack' (a common suffix for tools and equipment), though the exact etymology is uncertain. May relate to 'croix' (cross) if it refers to crossed carrying straps.
Before modern transportation, 'crojacks' were essential—merchants and travelers would use them to balance loads on pack animals, and the design had to distribute weight perfectly or the animal would be injured during long journeys.
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