COLNbrook, a town of Buckinghamshire in England, seated on the river Coln, which separates this county from Middlesex. It is a great thoroughfare on the western road, and has several good inns. There are some small islands formed in its neighbourhood by the different branches of the river Coln, where the Danes are supposed to have sheltered themselves from the attacks of Alfred. W. Long. 0. 25. N. Lat. 51. 30.