On the rocks is an idiom with two different, distinct meanings. We will examine the meaning of the idiom on the rocks, where it came from, and some examples of its use in sentences.
On the rocks may mean to serve a beverage with ice in it. The “rocks” referred to in this expression are ice cubes. Most often, a beverage that is served on the rocks is an alcoholic drink.
On the rocks may also be used to mean that an institution, endeavor or romantic relationship is on the brink of inevitable failure. A marriage that is headed for divorce may be said to be on the rocks. A failing business may be said to be on the rocks. The idiom on the rocks, used in this manner, is derived from the image of a ship running aground and breaking apart on a rocky outcropping. The idiom on the rocks has been in use since at least the 1800s.
Examples
At their sister restaurant, O-Ku, it’s mixed as a cocktail and served on the rocks. (The Atlanta Journal Constitution)
This delicious concoction of half dry vermouth and half sweet vermouth served on the rocks was uncommon and most bartenders needed an explanation of it when he would order. (St. Catherine’s Standard)
Does Netanyahu’s failure to hit 61-seats place annexation on the rocks? (The Jerusalem Post)
She later hit back at claims their marriage is on the rocks and absence from home during Strictly and his appearance on the live shows has put a strain on their relationship. (The Sun)