Definition of "simultaneously"

The cradle-rocking and the song would cease simultaneously for a moment, and an exclamation at highest vocal pitch would take the place of the melody.

1891, Thomas Hardy, Tess of the d'Urbervilles, volume 1, London: James R. Osgood, McIlvaine and Co., page 29

The hens woke up squawking with terror because they had all dreamed simultaneously of hearing a gun go off in the distance.

1945 August 17, George Orwell [pseudonym; Eric Arthur Blair], chapter 6, in Animal Farm […], London: Secker & Warburg

Hidden behind thickets of acronyms and gorse bushes of detail, a new great game is under way across the globe. Some call it geoeconomics, but it's geopolitics too. The current power play consists of an extraordinary range of countries simultaneously sitting down to negotiate big free trade and investment agreements.

2013 July 19, Timothy Garton Ash, “Where Dr Pangloss meets Machiavelli”, in The Guardian Weekly, volume 189, number 6, page 18