It normally means "in succession" or "one after the other without interruption". For example, "three years on the trot" means three consecutive years. "trot" means a brisk pace.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
This is actually a Naval term. Submarines always moor alongside on a berth designated as a 'trot'. There are two 'trot' sentries on watch alongside at all times, an 'upper trot' who is responsible for the outside part of the submarine and the gangway and a 'lower trot' who is watchkeeping the internal forward part of the submarine. When there are two or three submarines alongside each other mo