1 What It Means
The empty space left at the top of a bottle, cask, or tank, or the amount by which a container falls short of being full.
2 Caught in the Wild
The wine had a low ullage for its age, with the level well down into the shoulder of the bottle.
Illustrative usage. · Undated
3 Where It Comes From
Ullage comes from Old French ouillage, from ouiller, to fill a cask up to the bung. That verb traces back to ouil, an old word for eye, which in cooperage meant the bunghole. Ouil descends from Latin oculus. English took the word in during the 1400s through the wine trade, then kept it in a narrow lane. Customs officers, vintners, shippers and auction houses needed it. Ordinary drinkers never did, because a household bottle is either opened or it isn't. The word stayed in ledgers and cellar books, where it measured loss, so it never drifted into everyday speech.
4 The World Behind the Word
Wine leaks and evaporates, even when it looks sealed. Over decades, a tiny amount slips past the cork, and the gap beneath it grows. Collectors read that gap through the glass. Auction houses grade old bottles by fill level, with labels such as high fill, into neck, and top shoulder, and each step down usually means a lower price and a higher risk of spoilage. Cellar workers once topped up casks for the same reason, since air in a barrel invites trouble. Rocketry borrowed the word for a stranger version of the problem. In weightlessness, liquid fuel floats in its tank instead of settling at the bottom, so a pump can swallow gas. Engineers fire small ullage motors to nudge the propellant into place before the main engine lights. Same word, same gap, very different stakes.
5 Use It Yourself
Ullage earns its keep in the kitchen and the group chat. Tell your sister the cold brew pitcher has a lot of ullage, and you have said it is mostly empty, with style. It also suits a cellar tour, or a friend who just bought an old bottle online. Ask about the ullage before you pay. The register trap is that most people will hear a made-up word, so say it with a straight face and a gesture toward the empty part.
Try it out loud
The seller swore the bottle was fine, but the ullage was down in the shoulder, and I walked away.
🗝️The Deep Cut File
Ullage once had a bureaucratic edge. When casks of wine or spirits crossed oceans, some liquid was always lost to leakage and evaporation, and merchants and tax officials argued over who bore the loss. Ullage became a measure of that shortfall, and it turned up in shipping and customs accounts. Its modern fame comes from spaceflight. Apollo-era rockets used ullage motors and the term still appears in launch vehicle documentation. So a word that began with a cask of wine ended up inside the engineering of vehicles that leave the planet, still describing the same stubborn gap.
