I found the word, “at turns” in the beginning sentence of the article of Time magazine (September 18) titled, “How Mitt Romney’s Luck Ran Out” that reads:
“For a good long while, Mitt Romney was the luckiest man in politics. He joined the 2012 race as the default Republican front runner after more-formidable challengers chose not to run. His declared rivals were at turns ineffectual, ridiculous, or self-destructive — granting Romney a fairly easy, if occasionally fraught, path to the nomination.
I was almost overlooking the phrase, “at turns” as a commonplace idiom, but curiously enough I couldn’t find this phrase in any of Cambridge, Oxford, OALED, and Merriam-Webster Dictionary though they register “by turns,” “in turn,” “at every turn” “on the turn,” and you can name it.
On the other hand, GoogleNgram indicates track of pretty high usage of “at turns” dating back to 1840.
Because no dictionary I consulted does offer me the definition, I cannot get exact idea of ‘at turns.’ Is it the same as ‘at every turn,” “by turn(s),” "one after another,"or “respectively?” Is “at turns” a familiar idiom as these idioms?
Of course it’s freedom of the editors of dictionaries what words and idioms they pick up in their dictionaries. But I wonder why none of wellknown English dictionaries accommodates the idiom of which high incidence of use being evidenced in NGram.