1.
If two or more people or things are on a ~, there is likely to be a sudden and violent disagreement between them.
The two communities are now on a ~...
Britain’s universities are set on a ~ with the government.
N-SING: usu on a N, oft N with n
2.
If two or more people or things are on a ~, they are likely to meet and crash into each other violently.
There is an asteroid on a ~ with the Earth.
N-SING: usu on a N, oft N with n