Check whether an update for a particular package is available without upgrading

[Keith Christian <keith1christian@gmail.com>]

On a Wheezy system, I have used aptitude exclusively for
updates/upgrades, etc.  Looking for a command line option to use with
aptitude to check whether updates are available for a single arbitrary
package, e.g. "debian-reference-en" for example.

Have searched the WWW and man pages without finding anything like "dry
run" or "show possible upgrades" specifically for aptitude.
Previously I've seen recommendations to use aptitude or apt-get for
updates/upgrades but not mix them due to creating inconsistencies in
the package file listings, or something.  (Maybe this isn't an issue
in 2014?)

Again, want this for a single package, but suppose a list of all
potential upgrades would be OK as long as it's a listing only and
doesn't engage in an actual package upgrade.

Thanks for any insight, explanation, methods, command line arguments, etc.