In an alternating cycle; in successive or rotating turns. I think something was wrong, for her manner was by turns welcoming and cold, which made for a disconcerting evening. My wife and I divide household tasks by turns.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
by ˈturn(s)used when talking of contrasting feelings or actions which follow each other: He looked surprised, worried and angry by turn. ♢ When they told me I had got the job in New York, I felt by turns excited and anxious.
Farlex Partner Idioms Dictionary © Farlex 2017