on a tangent

Idioms  

1. On a sudden digression or change of course, as in The professor's hard to follow; he's always off on a tangent. This phrase often occurs in the idioms, as in The witness was convincing until he went off on a tangent. This expression alludes to the geometric tangent—a line or curve that touches but does not intersect with another line or curve. [Second half of 1700s]

---

Example Sentences

"Some of them will run straight, some of them will not start at all, some of them will go off on a tangent or bite each other," she explained.

From BBC • Apr. 19, 2025

Maher tried to ask a follow-up after Conway went on a tangent about Hillary Clinton, whose presidential campaign ended almost eight years ago, before being interrupted.

From Salon • May 4, 2024

He deftly maneuvers the conversation when necessary but also knows when to let one of his co-hosts or a guest go off on a tangent, which often leads to the most interesting material.

From Washington Post • Mar. 16, 2023

Monáe brings a carefree spirit to thoughtful conversation — happy to veer off on a tangent, deeply enmeshed in the issues raised by her high-concept work.

From Los Angeles Times • Apr. 21, 2022

Marcus goes off on a tangent about different schools that his girlfriend, Tiffanie, is looking at and how he’s going to a community college near whatever school she chooses.

From "Dumplin'" by Julie Murphy