pack mule Share definition Flag Someone who can be riden, or be forced to carry heavy objects for no pay or gratitude. RN is my PACK MULE. pack mule by Zach G. November 9, 2003 Words you can keep railfan mug chonk mug chud mug based mug 67 mug slime mug mogging mug chopped mug thot mug glazing mug huzz mug yams mug larp mug unc mug cracked mug simp mug baddie mug bop mug lolcow mug