All in a breath. Without taking breath. (Latin, continenti spiritu.)
“You might have saved your breath to cool your porridge.” —Mrs. Gaskell: Libbie Marsh (Era 111).
“ `I see her,' replied I, catching my breath with joy.” —Capt. Marryat: Peter Simple.
To hold one's breath. Voluntarily to cease breathing for a time. To take breath. To cease for a little time from some exertion in order to recover from exhaustion of breath. Under one's breath. In a whisper or undertone of voice.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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