"one umbrella" is a correct and usable phrase in written English.
It can be used when referring to a single instance of an umbrella. For example: When the sky suddenly darkened, I was glad I had brought one umbrella.
For convenience, the authors use the rubric of the so-called Papez circuit to subsume under one umbrella circuits that focus on connections with the hippocampal formation.
Since then he has been on an acquisition spree, consolidating all his media and sports holdings under one umbrella.
The entire process and invoicing is under one umbrella.
"We now need to get together under one umbrella.
Nato shelters them under one umbrella, held by the US.
"It will all be put under one umbrella," Mr. Kelly said.
"Now that will all be brought under one umbrella and people can apply in one place".
I want to see all this stuff under one umbrella of creativity.
"Corruption and political donations have to be seen under one umbrella," he said.
To that end, HCUK has successfully brought many different faith denominations and disparate Hindu communities under one umbrella.
Dutch bank Rabobank has a similar model – it grouped dozens of former farming societies under one umbrella.
