When speaking of a group of people and referring to a body part of which there is only one (e.g. head, nose, mouth, etc.), do we use the singular or plural form? Which of the following is correct, or are both possible?

Our stomach is full.

Our stomachs are full.

• Remember, although there is only one per person, you are talking about the entire group, and within the group there is not only one such body part; if you have ten people, you have ten stomachs. Plural is the only possible choice. Commented May 9, 2013 at 8:17
• Commented May 9, 2013 at 21:21
• How would I know if my question is a duplicate when the field doesn't seem to show me any related answers as I'm typing my own question? And I don't think it's possible for me to go through 50+ pages of the "singular-plural" discussion when I have to answer my students within a day. I'd really like to know how you could help me with this problem. Commented May 10, 2013 at 0:55

In both cases:

Let's put our heads together and solve this problem quickly.

and

Now that our stomachs are full, we can think more clearly about the problem.

use the plural. Using the singular suggests a joint body part, which is not the case.

• But (A) idioms may not 'follow the rule': They have not got a head for heights. and They have not got the stomach to fight for three more weeks. And idioms get very close to literal usage (Use your brain/s!) (B) The rhetorical device of addressing a crowd in a 1-to-1 manner is well known: 'Hold your fork in your left hand and ...' Commented Dec 14, 2014 at 22:32

For your example, you should definitely use the plural, however there can sometimes be ambiguity in English. For example, how many legs get broken in this sentence?

John and James collided on the ski slope and broke their legs.

A better version would be

John and James collided on the ski slope and each broke his leg.

But what if it's John and Jane?

John and Jane collided on the ski slope and each broke their leg?

or

John and Jane collided on the ski slope and each broke a leg?

Neither works perfectly, in my opinion, so it can be an awkward way of saying things.

• The obvious way to avoid the problem is not to ski. Commented May 9, 2013 at 10:12