Mule
Definition 1 of 4
Pro Tip 1/3
Animal Hybrid
Understand that 'mule' refers to a specific animal hybrid and not just any mixed-breed animal. Crossbreeding a pony and a donkey will not produce a mule.
Pro Tip 2/3
Workload Carrier
'Mule' highlights the animal's historic role in hauling burdens, making it a metaphor for bearing heavy loads. He's carrying all our backpacks, our very own mule.
Pro Tip 3/3
Stubborn Reputation
Mules are famously stubborn, so 'stubborn as a mule' implies great obstinacy. I tried to change his mind, but he's stubborn as a mule.