Something, like a piece of jewellery or an antique, that has been passed down in a family line. These things often have great sentimental value, whether they are worth a lot of money or not.

Heir - a descendant
Loom - a tool
My Oma left me some heirloom jewellery when she passed away. Some may think that the jewellery is junk, but it is precious to me.
by bbeingcool August 20, 2011
Refers to the testicles of mammals
Bobby doesn't mark his territory anymore since he lost his heirloom
by RidiculousSlang October 13, 2017
Shit passed from generation to generation.
Super old clutter.
Meaningless garbage we pretend is worth our attention.
Person 1: buts it’s a family heirloom we can’t....
Person 2: don’t you dare finish that sentence
by Ninja-de-hissinyoface September 13, 2020
The names and phone numbers that get passed along now that your friend is seeing someone exclusively.
Now that Jason and Cindy are exclusive, she said she'd pass along some of her Heirloom Cock to us. Dibs on the guy with all the tattoos.
by Ephemily February 27, 2012
wanna be gang slang for my passed on valubles or money.
hey G when my pops croked he passed me his heirloom vegetables.
by Mat August 1, 2004