in a body = All together; as a group

I already understand and so ask NOT about the above definition.
Instead, my problem is: As a preposition, in confuses me. Why was as not used instead?

Am I right that this prepositional phrase is an idiom? Even if so, what are some right ways of interpreting it so that it feels reasonable and intuitive?

Footnote: I encountered this while reading Etymonline for 'drove {noun}'. I had been stuck for 5 mins before I suspected a figurative meaning and tried the dictionary.

  • Not sure but here is how I look at it-- when you refer, you do it "as a group", and when you mean 'acting toward something', you call it "in a group". Example: They came in a group and vandalized the premises over "They are not different, consider them as a group".
    – Maulik V
    Apr 9, 2015 at 6:35
  • I believe the choice of preposition is determined by the verb. Some verbs want "in", some want "as", and some don't care.
    – TimR
    Apr 9, 2015 at 11:48
  • This might be something particular the BrE usage, or maybe just something falling out of favor in modern English. In my version of AmE, "in a body" is very uncommon when used in the same sense as "The workers went in a body to the rally."
    – ColleenV
    Apr 9, 2015 at 17:23

1 Answer 1


It isn't an idiom.

Compare: in a group | as a group.

They ran in a group to see the fist-fight taking place behind the gym.
The members of the book club went as a group to a Broadway play.

In a {group, body} refers to the physical formation.

As a {group, body} refers to a set of individuals united in some common purpose or a set of items sharing a common property.

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